diff --git a/build/AzurePipelineTemplates/CsWinRT-BuildAndTest-Stage.yml b/build/AzurePipelineTemplates/CsWinRT-BuildAndTest-Stage.yml
index b64b411bb..b99c24e07 100644
--- a/build/AzurePipelineTemplates/CsWinRT-BuildAndTest-Stage.yml
+++ b/build/AzurePipelineTemplates/CsWinRT-BuildAndTest-Stage.yml
@@ -93,6 +93,18 @@ stages:
         script: |
           dir _build\$(BuildPlatform)\$(BuildConfiguration)\AuthoringConsumptionTest\bin
           _build\$(BuildPlatform)\$(BuildConfiguration)\AuthoringConsumptionTest\bin\AuthoringConsumptionTest.exe --gtest_output=xml:AUTHORINGTEST-$(Build.BuildNumber).xml 
+          exit /b 0
+
+# Run WUX Tests
+    - task: CmdLine@2
+      displayName: Run WUX Tests
+      condition: and(succeeded(), or(eq(variables['BuildPlatform'], 'x86'), eq(variables['BuildPlatform'], 'x64')))
+      continueOnError: True
+      inputs:
+        workingDirectory: $(Build.SourcesDirectory)\src
+        script: |
+          dir _build\$(BuildPlatform)\$(BuildConfiguration)\AuthoringWuxConsumptionTest\bin
+          _build\$(BuildPlatform)\$(BuildConfiguration)\AuthoringWuxConsumptionTest\bin\AuthoringWuxConsumptionTest.exe --gtest_output=xml:AUTHORINGWUXTEST-$(Build.BuildNumber).xml 
           exit /b 0 
 
 # Run Functional Tests  
diff --git a/nuget/Microsoft.Windows.CsWinRT.Authoring.targets b/nuget/Microsoft.Windows.CsWinRT.Authoring.targets
index 98f03ea58..f020d04fc 100644
--- a/nuget/Microsoft.Windows.CsWinRT.Authoring.targets
+++ b/nuget/Microsoft.Windows.CsWinRT.Authoring.targets
@@ -33,6 +33,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
     <CompilerVisibleProperty Include="CsWinRTWindowsMetadata" />
     <CompilerVisibleProperty Include="CsWinRTGenerateProjection" />
     <CompilerVisibleProperty Include="CsWinRTAuthoringInputs" />
+    <CompilerVisibleProperty Include="CsWinRTUIXamlProjections" />
   </ItemGroup>
 
   <!-- Note this runs before the msbuild editor config file is generated because that is what is used to pass properties to the source generator. -->
diff --git a/nuget/Microsoft.Windows.CsWinRT.targets b/nuget/Microsoft.Windows.CsWinRT.targets
index 64abdcf40..8fe95eaa2 100644
--- a/nuget/Microsoft.Windows.CsWinRT.targets
+++ b/nuget/Microsoft.Windows.CsWinRT.targets
@@ -289,6 +289,13 @@ $(CsWinRTInternalProjection)
     </ItemGroup>
   </Target>
 
+  <ItemGroup>
+    <RuntimeHostConfigurationOption Include="CsWinRT.UiXamlMode" Condition="'$(CsWinRTUiXamlMode)' != ''">
+      <Value>$(CsWinRTUiXamlMode)</Value>
+      <Trim>true</Trim>
+    </RuntimeHostConfigurationOption>
+  </ItemGroup>
+
   <Import Project="$(MSBuildThisFileDirectory)Microsoft.Windows.CsWinRT.Prerelease.targets" Condition="Exists('$(MSBuildThisFileDirectory)Microsoft.Windows.CsWinRT.Prerelease.targets')"/>
   <Import Project="$(MSBuildThisFileDirectory)Microsoft.Windows.CsWinRT.Authoring.targets" Condition="'$(CsWinRTComponent)' == 'true'"/>
   <Import Project="$(MSBuildThisFileDirectory)Microsoft.Windows.CsWinRT.IIDOptimizer.targets" Condition="'$(CsWinRTIIDOptimizerOptOut)' != 'true'"/>
@@ -338,6 +345,16 @@ $(CsWinRTInternalProjection)
     <RuntimeHostConfigurationOption Include="CSWINRT_ENABLE_IDYNAMICINTERFACECASTABLE"
                                     Value="$(CsWinRTEnableIDynamicInterfaceCastableSupport)"
                                     Trim="true" />
+
+    <!-- CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS switch-->
+    <RuntimeHostConfigurationOption Include="CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS" Condition="'$(CsWinRTUIXamlProjections)' == 'WindowsUIXaml'">
+      <Value>true</Value>
+      <Trim>true</Trim>
+    </RuntimeHostConfigurationOption>
+    <RuntimeHostConfigurationOption Include="CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS" Condition="'$(CsWinRTUIXamlProjections)' != 'WindowsUIXaml'">
+      <Value>false</Value>
+      <Trim>true</Trim>
+    </RuntimeHostConfigurationOption>
   </ItemGroup>
 
 </Project>
diff --git a/src/Authoring/WinRT.SourceGenerator/AotOptimizer.cs b/src/Authoring/WinRT.SourceGenerator/AotOptimizer.cs
index 0df8eaf9a..052078819 100644
--- a/src/Authoring/WinRT.SourceGenerator/AotOptimizer.cs
+++ b/src/Authoring/WinRT.SourceGenerator/AotOptimizer.cs
@@ -22,10 +22,14 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             var properties = context.AnalyzerConfigOptionsProvider.Select(static (provider, _) => 
                 (provider.IsCsWinRTAotOptimizerEnabled(), provider.IsCsWinRTComponent(), provider.IsCsWinRTCcwLookupTableGeneratorEnabled()));
 
+            var typeMapper = context.AnalyzerConfigOptionsProvider.Select((options, ct) => options.GlobalOptions.GetUIXamlProjectionsMode()).Select((mode, ct) => new TypeMapper(mode));
+
             var vtablesToAddFromClassTypes = context.SyntaxProvider.CreateSyntaxProvider(
                     static (n, _) => NeedVtableAttribute(n),
-                    static (n, _) => GetVtableAttributeToAdd(n, false)
-                ).Where(static vtableAttribute => vtableAttribute != default);
+                    static (n, _) => n)
+                .Combine(typeMapper)
+                .Select((t, _) => GetVtableAttributeToAdd(t.Left, t.Right, false))
+                .Where(static vtableAttribute => vtableAttribute != default);
 
             var vtableAttributesToAdd = vtablesToAddFromClassTypes.Select(static (vtable, _) => vtable.Item1);
             var adapterTypesToAddOnLookupTable = vtablesToAddFromClassTypes.SelectMany(static (vtable, _) => vtable.Item2);
@@ -36,32 +40,39 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             // that will already be generated by the component generator.
             var vtablesFromComponentTypes = context.SyntaxProvider.CreateSyntaxProvider(
                     static (n, _) => IsComponentType(n),
-                    static (n, _) => GetVtableAttributeToAdd(n, true)
-                ).Where(static vtableAttribute => vtableAttribute != default).Collect().Combine(properties).
-                  // Get component types if only authoring scenario
-                  SelectMany(static ((ImmutableArray<(VtableAttribute vtableAttribute, EquatableArray<VtableAttribute> adapterTypes)> classTypes, (bool, bool isCsWinRTComponent, bool) properties) value, CancellationToken _) =>
+                    static (n, _) => n)
+                .Combine(typeMapper)
+                .Select((t, _) => GetVtableAttributeToAdd(t.Left, t.Right, true))
+                .Where(static vtableAttribute => vtableAttribute != default).Collect()
+                .Combine(properties)
+                // Get component types if only authoring scenario
+                .SelectMany(static ((ImmutableArray<(VtableAttribute vtableAttribute, EquatableArray<VtableAttribute> adapterTypes)> classTypes, (bool, bool isCsWinRTComponent, bool) properties) value, CancellationToken _) =>
                         value.properties.isCsWinRTComponent ? value.classTypes : ImmutableArray<(VtableAttribute, EquatableArray<VtableAttribute>)>.Empty);
 
             var instantiatedTypesToAddOnLookupTable = context.SyntaxProvider.CreateSyntaxProvider(
                     static (n, _) => NeedVtableOnLookupTable(n),
-                    static (n, _) => GetVtableAttributesToAddOnLookupTable(n)
-                ).Combine(properties)
-                 // Get component types if only authoring scenario
-                 .Select(static (((EquatableArray<VtableAttribute> lookupTable, EquatableArray<VtableAttribute> componentLookupTable) vtableAttributes, (bool, bool isCsWinRTComponent, bool) properties) value, CancellationToken _) =>
-                        value.properties.isCsWinRTComponent ? value.vtableAttributes.componentLookupTable : value.vtableAttributes.lookupTable)
-                 .SelectMany(static (vtable, _) => vtable).
-                  Where(static vtableAttribute => vtableAttribute != null);
+                    static (n, _) => n)
+                .Combine(typeMapper)
+                .Select((t, _) => GetVtableAttributesToAddOnLookupTable(t.Left, t.Right))
+                .Combine(properties)
+                // Get component types if only authoring scenario
+                .Select(static (((EquatableArray<VtableAttribute> lookupTable, EquatableArray<VtableAttribute> componentLookupTable) vtableAttributes, (bool, bool isCsWinRTComponent, bool) properties) value, CancellationToken _) =>
+                    value.properties.isCsWinRTComponent ? value.vtableAttributes.componentLookupTable : value.vtableAttributes.lookupTable)
+                .SelectMany(static (vtable, _) => vtable)
+                .Where(static vtableAttribute => vtableAttribute != null);
 
             var instantiatedTaskAdapters = context.SyntaxProvider.CreateSyntaxProvider(
                     static (n, _) => IsAsyncOperationMethodCall(n),
-                    static (n, _) => GetVtableAttributesForTaskAdapters(n)
-                ).Where(static vtableAttribute => vtableAttribute != default).
-                 Combine(properties).
-                  // Get component types if only authoring scenario
-                  Select(static (((VtableAttribute vtableAttribute, VtableAttribute componentVtableAttribute) vtableAttributes, (bool, bool isCsWinRTComponent, bool) properties) value, CancellationToken _) =>
-                        value.properties.isCsWinRTComponent ? value.vtableAttributes.componentVtableAttribute : value.vtableAttributes.vtableAttribute).
-                  Where(static vtableAttribute => vtableAttribute != default).
-                  Collect();
+                    static (n, _) => n)
+                .Combine(typeMapper)
+                .Select((data, ct) => GetVtableAttributesForTaskAdapters(data.Left, data.Right))
+                .Where(static vtableAttribute => vtableAttribute != default)
+                .Combine(properties)
+                 // Get component types if only authoring scenario
+                 .Select(static (((VtableAttribute vtableAttribute, VtableAttribute componentVtableAttribute) vtableAttributes, (bool, bool isCsWinRTComponent, bool) properties) value, CancellationToken _) =>
+                        value.properties.isCsWinRTComponent ? value.vtableAttributes.componentVtableAttribute : value.vtableAttributes.vtableAttribute)
+                  .Where(static vtableAttribute => vtableAttribute != default)
+                  .Collect();
 
             // Merge both adapter types list and instantiated types list 
             var vtablesToAddOnLookupTable = 
@@ -112,19 +123,22 @@ private static bool IsComponentType(SyntaxNode node)
                 !GeneratorHelper.IsWinRTType(declaration); // Making sure it isn't an RCW we are projecting.
         }
 
-        private static (VtableAttribute, EquatableArray<VtableAttribute>) GetVtableAttributeToAdd(GeneratorSyntaxContext context, bool checkForComponentTypes)
+        private static (VtableAttribute, EquatableArray<VtableAttribute>) GetVtableAttributeToAdd(
+            GeneratorSyntaxContext context,
+            TypeMapper typeMapper,
+            bool checkForComponentTypes)
         {
             var isWinRTTypeFunc = checkForComponentTypes ? 
                 GeneratorHelper.IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(context.SemanticModel.Compilation) :
                 GeneratorHelper.IsWinRTType;
             var symbol = context.SemanticModel.GetDeclaredSymbol(context.Node as ClassDeclarationSyntax);
-            var vtableAttribute = GetVtableAttributeToAdd(symbol, isWinRTTypeFunc, context.SemanticModel.Compilation, false);
+            var vtableAttribute = GetVtableAttributeToAdd(symbol, isWinRTTypeFunc, typeMapper, context.SemanticModel.Compilation, false);
             if (vtableAttribute != default)
             {
                 HashSet<VtableAttribute> vtableAttributesForLookupTable = [];
                 // Add any adapter types which may be needed if certain functions
                 // from some known interfaces are called.
-                AddVtableAdapterTypeForKnownInterface(symbol, context.SemanticModel.Compilation, isWinRTTypeFunc, vtableAttributesForLookupTable);
+                AddVtableAdapterTypeForKnownInterface(symbol, context.SemanticModel.Compilation, isWinRTTypeFunc, typeMapper, vtableAttributesForLookupTable);
                 return (vtableAttribute, vtableAttributesForLookupTable.ToImmutableArray());
             }
 
@@ -187,7 +201,7 @@ static bool IsAsyncOperationMethodCall(SyntaxNode node)
         // We do this both assuming this is not an authoring component and is an authoring
         // component as we don't know that at this stage and the results can vary based on that.
         // We will choose the right one later when we can combine with properties.
-        private static (VtableAttribute, VtableAttribute) GetVtableAttributesForTaskAdapters(GeneratorSyntaxContext context)
+        private static (VtableAttribute, VtableAttribute) GetVtableAttributesForTaskAdapters(GeneratorSyntaxContext context, TypeMapper typeMapper)
         {
             if (context.SemanticModel.GetSymbolInfo(context.Node as InvocationExpressionSyntax).Symbol is IMethodSymbol symbol)
             {
@@ -200,8 +214,8 @@ private static (VtableAttribute, VtableAttribute) GetVtableAttributesForTaskAdap
                         if (adpaterType is not null)
                         {
                             var constructedAdapterType = adpaterType.Construct([.. symbol.TypeArguments]);
-                            return (GetVtableAttributeToAdd(constructedAdapterType, GeneratorHelper.IsWinRTType, context.SemanticModel.Compilation, false), 
-                                    GetVtableAttributeToAdd(constructedAdapterType, GeneratorHelper.IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(context.SemanticModel.Compilation), context.SemanticModel.Compilation, false));
+                            return (GetVtableAttributeToAdd(constructedAdapterType, GeneratorHelper.IsWinRTType, typeMapper, context.SemanticModel.Compilation, false), 
+                                    GetVtableAttributeToAdd(constructedAdapterType, GeneratorHelper.IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(context.SemanticModel.Compilation), typeMapper, context.SemanticModel.Compilation, false));
                         }
                     }
                 }
@@ -306,7 +320,8 @@ private static string GetRuntimeClassName(INamedTypeSymbol type, Func<ISymbol, b
 
         internal static VtableAttribute GetVtableAttributeToAdd(
             ITypeSymbol symbol, 
-            Func<ISymbol, bool> isWinRTType, 
+            Func<ISymbol, TypeMapper, bool> isWinRTType, 
+            TypeMapper mapper,
             Compilation compilation,
             bool isAuthoring, 
             string authoringDefaultInterface = "")
@@ -316,7 +331,7 @@ internal static VtableAttribute GetVtableAttributeToAdd(
                 return default;
             }
 
-            if (GeneratorHelper.HasNonInstantiatedWinRTGeneric(symbol))
+            if (GeneratorHelper.HasNonInstantiatedWinRTGeneric(symbol, mapper))
             {
                 return default;
             }
@@ -333,18 +348,18 @@ internal static VtableAttribute GetVtableAttributeToAdd(
             // use the specified one.  Also for authoring scenarios where we call this for authored WinRT types,
             // don't generate the runtimeclass name for them as we will rely on the full name for them as we do today.
             var checkForRuntimeClasName = !GeneratorHelper.HasWinRTRuntimeClassNameAttribute(symbol, compilation) && 
-                (!isAuthoring || (isAuthoring && !isWinRTType(symbol)));
+                (!isAuthoring || (isAuthoring && !isWinRTType(symbol, mapper)));
             INamedTypeSymbol interfaceToUseForRuntimeClassName = null;
             foreach (var iface in symbol.AllInterfaces)
             {
-                if (isWinRTType(iface))
+                if (isWinRTType(iface, mapper))
                 {
                     interfacesToAddToVtable.Add(ToFullyQualifiedString(iface));
                     AddGenericInterfaceInstantiation(iface);
                     CheckForInterfaceToUseForRuntimeClassName(iface);
                 }
 
-                if (iface.IsGenericType && TryGetCompatibleWindowsRuntimeTypesForVariantType(iface, null, isWinRTType, out var compatibleIfaces))
+                if (iface.IsGenericType && TryGetCompatibleWindowsRuntimeTypesForVariantType(iface, mapper, null, isWinRTType, out var compatibleIfaces))
                 {
                     foreach (var compatibleIface in compatibleIfaces)
                     {
@@ -426,7 +441,7 @@ internal static VtableAttribute GetVtableAttributeToAdd(
                 symbol is IArrayTypeSymbol,
                 isDelegate,
                 symbol.DeclaredAccessibility == Accessibility.Public,
-                GetRuntimeClassName(interfaceToUseForRuntimeClassName, isWinRTType));
+                GetRuntimeClassName(interfaceToUseForRuntimeClassName, type => isWinRTType(type, mapper)));
 
             void AddGenericInterfaceInstantiation(INamedTypeSymbol iface)
             {
@@ -445,7 +460,7 @@ void AddGenericInterfaceInstantiation(INamedTypeSymbol iface)
 
                         genericParameters.Add(new GenericParameter(
                             ToFullyQualifiedString(genericParameter),
-                            GeneratorHelper.GetAbiType(genericParameter),
+                            GeneratorHelper.GetAbiType(genericParameter, mapper),
                             genericParameter.TypeKind));
                     }
 
@@ -479,7 +494,7 @@ void CheckForInterfaceToUseForRuntimeClassName(INamedTypeSymbol iface)
             }
         }
 
-        private static bool TryGetCompatibleWindowsRuntimeTypesForVariantType(INamedTypeSymbol type, Stack<INamedTypeSymbol> typeStack, Func<ISymbol, bool> isWinRTType, out IList<INamedTypeSymbol> compatibleTypes)
+        private static bool TryGetCompatibleWindowsRuntimeTypesForVariantType(INamedTypeSymbol type, TypeMapper mapper, Stack<INamedTypeSymbol> typeStack, Func<ISymbol, TypeMapper, bool> isWinRTType, out IList<INamedTypeSymbol> compatibleTypes)
         {
             compatibleTypes = null;
 
@@ -492,7 +507,7 @@ private static bool TryGetCompatibleWindowsRuntimeTypesForVariantType(INamedType
             }
 
             var definition = type.OriginalDefinition;
-            if (!isWinRTType(definition))
+            if (!isWinRTType(definition, mapper))
             {
                 return false;
             }
@@ -512,20 +527,20 @@ private static bool TryGetCompatibleWindowsRuntimeTypesForVariantType(INamedType
 
             HashSet<ITypeSymbol> compatibleTypesForGeneric = new(SymbolEqualityComparer.Default);
 
-            if (isWinRTType(type.TypeArguments[0]))
+            if (isWinRTType(type.TypeArguments[0], mapper))
             {
                 compatibleTypesForGeneric.Add(type.TypeArguments[0]);
             }
 
             foreach (var iface in type.TypeArguments[0].AllInterfaces)
             {
-                if (isWinRTType(iface))
+                if (isWinRTType(iface, mapper))
                 {
                     compatibleTypesForGeneric.Add(iface);
                 }
 
                 if (iface.IsGenericType
-                    && TryGetCompatibleWindowsRuntimeTypesForVariantType(iface, typeStack, isWinRTType, out var compatibleIfaces))
+                    && TryGetCompatibleWindowsRuntimeTypesForVariantType(iface, mapper, typeStack, isWinRTType, out var compatibleIfaces))
                 {
                     compatibleTypesForGeneric.UnionWith(compatibleIfaces);
                 }
@@ -534,7 +549,7 @@ private static bool TryGetCompatibleWindowsRuntimeTypesForVariantType(INamedType
             var baseType = type.TypeArguments[0].BaseType;
             while (baseType != null)
             {
-                if (isWinRTType(baseType))
+                if (isWinRTType(baseType, mapper))
                 {
                     compatibleTypesForGeneric.Add(baseType);
                 }
@@ -837,18 +852,21 @@ node is VariableDeclarationSyntax ||
                     node is ReturnStatementSyntax;
         }
 
-        private static (EquatableArray<VtableAttribute>, EquatableArray<VtableAttribute>) GetVtableAttributesToAddOnLookupTable(GeneratorSyntaxContext context)
+        private static (EquatableArray<VtableAttribute>, EquatableArray<VtableAttribute>) GetVtableAttributesToAddOnLookupTable(
+            GeneratorSyntaxContext context,
+            TypeMapper typeMapper)
         {
             // Get the lookup table as if we are running in an authoring component scenario and as if we are not
             // and then use the properties later on when we have access to it to check if we are to choose the right one.
             // Otherwise we will end up generating lookup tables which don't have vtable entries for authoring types.
-            return (GetVtableAttributesToAddOnLookupTable(context, GeneratorHelper.IsWinRTType), 
-                    GetVtableAttributesToAddOnLookupTable(context, GeneratorHelper.IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(context.SemanticModel.Compilation)));
+            return (GetVtableAttributesToAddOnLookupTable(context, typeMapper, GeneratorHelper.IsWinRTType), 
+                    GetVtableAttributesToAddOnLookupTable(context, typeMapper, GeneratorHelper.IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(context.SemanticModel.Compilation)));
         }
 
         private static EquatableArray<VtableAttribute> GetVtableAttributesToAddOnLookupTable(
             GeneratorSyntaxContext context,
-            Func<ISymbol, bool> isWinRTType)
+            TypeMapper typeMapper,
+            Func<ISymbol, TypeMapper, bool> isWinRTType)
         {
             HashSet<ITypeSymbol> visitedTypes = new(SymbolEqualityComparer.Default);
             HashSet<VtableAttribute> vtableAttributes = new();
@@ -862,7 +880,7 @@ private static EquatableArray<VtableAttribute> GetVtableAttributesToAddOnLookupT
                     // and end up calling a projection function (i.e. ones generated by XAML compiler)
                     // In theory, another library can also be called which can call a projected function
                     // but not handling those scenarios for now.
-                    (isWinRTType(methodSymbol.ContainingSymbol) ||
+                    (isWinRTType(methodSymbol.ContainingSymbol, typeMapper) ||
                      SymbolEqualityComparer.Default.Equals(methodSymbol.ContainingAssembly, context.SemanticModel.Compilation.Assembly)))
                 {
                     // Get the concrete types directly from the argument rather than
@@ -891,13 +909,13 @@ private static EquatableArray<VtableAttribute> GetVtableAttributesToAddOnLookupT
             {
                 var leftSymbol = context.SemanticModel.GetSymbolInfo(assignment.Left).Symbol;
                 if (leftSymbol is IPropertySymbol propertySymbol &&
-                    (isWinRTType(propertySymbol.ContainingSymbol) ||
+                    (isWinRTType(propertySymbol.ContainingSymbol, typeMapper) ||
                      SymbolEqualityComparer.Default.Equals(propertySymbol.ContainingAssembly, context.SemanticModel.Compilation.Assembly)))
                 {
                     AddVtableAttributesForType(context.SemanticModel.GetTypeInfo(assignment.Right), propertySymbol.Type);
                 }
                 else if (leftSymbol is IFieldSymbol fieldSymbol &&
-                    (isWinRTType(fieldSymbol.ContainingSymbol) || 
+                    (isWinRTType(fieldSymbol.ContainingSymbol, typeMapper) || 
                      SymbolEqualityComparer.Default.Equals(fieldSymbol.ContainingAssembly, context.SemanticModel.Compilation.Assembly)))
                 {
                     AddVtableAttributesForType(context.SemanticModel.GetTypeInfo(assignment.Right), fieldSymbol.Type);
@@ -965,14 +983,14 @@ void AddVtableAttributesForType(Microsoft.CodeAnalysis.TypeInfo instantiatedType
                         }
                         visitedTypes.Add(arrayType);
 
-                        var vtableAtribute = GetVtableAttributeToAdd(arrayType, isWinRTType, context.SemanticModel.Compilation, false);
+                        var vtableAtribute = GetVtableAttributeToAdd(arrayType, isWinRTType, typeMapper, context.SemanticModel.Compilation, false);
                         if (vtableAtribute != default)
                         {
                             vtableAttributes.Add(vtableAtribute);
                         }
 
                         // Also add the enumerator type to the lookup table as the native caller can call it.
-                        AddEnumeratorAdapterForType(arrayType.ElementType, context.SemanticModel.Compilation, isWinRTType, vtableAttributes);
+                        AddEnumeratorAdapterForType(arrayType.ElementType, typeMapper, context.SemanticModel.Compilation, isWinRTType, vtableAttributes);
                     }
                 }
                 else if (instantiatedType.Type is not null || instantiatedType.ConvertedType is not null)
@@ -994,11 +1012,11 @@ void AddVtableAttributesForType(Microsoft.CodeAnalysis.TypeInfo instantiatedType
                     // information is available.
                     if (instantiatedTypeSymbol.TypeKind == TypeKind.Delegate &&
                         instantiatedTypeSymbol.MetadataName.Contains("`") &&
-                        isWinRTType(instantiatedTypeSymbol) &&
+                        isWinRTType(instantiatedTypeSymbol, typeMapper) &&
                         convertedToTypeSymbol.SpecialType == SpecialType.System_Object)
                     {
                         var argumentClassNamedTypeSymbol = instantiatedTypeSymbol as INamedTypeSymbol;
-                        vtableAttributes.Add(GetVtableAttributeToAdd(instantiatedTypeSymbol, isWinRTType, context.SemanticModel.Compilation, false));
+                        vtableAttributes.Add(GetVtableAttributeToAdd(instantiatedTypeSymbol, isWinRTType, typeMapper, context.SemanticModel.Compilation, false));
                     }
 
                     // This handles the case where the source generator wasn't able to run
@@ -1010,7 +1028,7 @@ void AddVtableAttributesForType(Microsoft.CodeAnalysis.TypeInfo instantiatedType
                     // library which happened to not run the AOT optimizer.  So as a best effort,
                     // we handle it here.
                     if (instantiatedTypeSymbol.TypeKind == TypeKind.Class &&
-                        (instantiatedTypeSymbol.MetadataName.Contains("`") || !isWinRTType(instantiatedTypeSymbol)) &&
+                        (instantiatedTypeSymbol.MetadataName.Contains("`") || !isWinRTType(instantiatedTypeSymbol, typeMapper)) &&
                         !GeneratorHelper.HasWinRTExposedTypeAttribute(instantiatedTypeSymbol) &&
                         // If the type is defined in the same assembly as what the source generator is running on,
                         // we let the WinRTExposedType attribute generator handle it.
@@ -1018,13 +1036,13 @@ void AddVtableAttributesForType(Microsoft.CodeAnalysis.TypeInfo instantiatedType
                         // Make sure the type we are passing is being boxed or cast to another interface.
                         !SymbolEqualityComparer.Default.Equals(instantiatedTypeSymbol, convertedToTypeSymbol))
                     {
-                        var vtableAtribute = GetVtableAttributeToAdd(instantiatedTypeSymbol, isWinRTType, context.SemanticModel.Compilation, false);
+                        var vtableAtribute = GetVtableAttributeToAdd(instantiatedTypeSymbol, isWinRTType, typeMapper, context.SemanticModel.Compilation, false);
                         if (vtableAtribute != default)
                         {
                             vtableAttributes.Add(vtableAtribute);
                         }
 
-                        AddVtableAdapterTypeForKnownInterface(instantiatedTypeSymbol, context.SemanticModel.Compilation, isWinRTType, vtableAttributes);
+                        AddVtableAdapterTypeForKnownInterface(instantiatedTypeSymbol, context.SemanticModel.Compilation, isWinRTType, typeMapper, vtableAttributes);
                     }
                 }
             }
@@ -1033,13 +1051,13 @@ void AddVtableAttributesForType(Microsoft.CodeAnalysis.TypeInfo instantiatedType
         // Any of the IEnumerable interfaces on the vtable can be used to get the enumerator.  Given IEnumerable is
         // a covariant interface, it means that we can end up getting an instance of the enumerable adapter for any one
         // of those covariant interfaces and thereby need vtable lookup entries for all of them.
-        private static void AddEnumeratorAdapterForType(ITypeSymbol type, Compilation compilation, Func<ISymbol, bool> isWinRTType, HashSet<VtableAttribute> vtableAttributes)
+        private static void AddEnumeratorAdapterForType(ITypeSymbol type, TypeMapper mapper, Compilation compilation, Func<ISymbol, TypeMapper, bool> isWinRTType, HashSet<VtableAttribute> vtableAttributes)
         {
             var enumerableType = compilation.GetTypeByMetadataName("System.Collections.Generic.IEnumerable`1");
             if (enumerableType != null)
             {
                 var constructedEnumerableType = enumerableType.Construct(type);
-                if (TryGetCompatibleWindowsRuntimeTypesForVariantType(constructedEnumerableType, null, isWinRTType, out var compatibleIfaces))
+                if (TryGetCompatibleWindowsRuntimeTypesForVariantType(constructedEnumerableType, mapper, null, isWinRTType, out var compatibleIfaces))
                 {
                     foreach (var compatibleIface in compatibleIfaces)
                     {
@@ -1050,7 +1068,7 @@ private static void AddEnumeratorAdapterForType(ITypeSymbol type, Compilation co
                             if (enumeratorAdapterType != null)
                             {
                                 var constructedEnumeratorAdapterType = enumeratorAdapterType.Construct(compatibleIface.TypeArguments[0]);
-                                var vtableAttribute = GetVtableAttributeToAdd(constructedEnumeratorAdapterType, isWinRTType, compilation, false);
+                                var vtableAttribute = GetVtableAttributeToAdd(constructedEnumeratorAdapterType, isWinRTType, mapper, compilation, false);
                                 if (vtableAttribute != default)
                                 {
                                     vtableAttributes.Add(vtableAttribute);
@@ -1062,13 +1080,13 @@ private static void AddEnumeratorAdapterForType(ITypeSymbol type, Compilation co
             }
         }
 
-        internal static void AddVtableAdapterTypeForKnownInterface(ITypeSymbol classType, Compilation compilation, Func<ISymbol, bool> isWinRTType, HashSet<VtableAttribute> vtableAttributes)
+        internal static void AddVtableAdapterTypeForKnownInterface(ITypeSymbol classType, Compilation compilation, Func<ISymbol, TypeMapper, bool> isWinRTType, TypeMapper mapper, HashSet<VtableAttribute> vtableAttributes)
         {
             foreach (var iface in classType.AllInterfaces)
             {
                 if (iface.MetadataName == "IEnumerable`1")
                 {
-                    AddEnumeratorAdapterForType(iface.TypeArguments[0], compilation, isWinRTType, vtableAttributes);
+                    AddEnumeratorAdapterForType(iface.TypeArguments[0], mapper, compilation, isWinRTType, vtableAttributes);
                 }
                 else if (iface.MetadataName == "IDictionary`2")
                 {
@@ -1088,7 +1106,7 @@ void LookupAndAddVtableAttributeForGenericType(string type, ImmutableArray<IType
                 if (genericType != default)
                 {
                     var constructedGenericType = genericType.Construct([.. genericArgs]);
-                    var vtableAttribute = GetVtableAttributeToAdd(constructedGenericType, isWinRTType, compilation, false);
+                    var vtableAttribute = GetVtableAttributeToAdd(constructedGenericType, isWinRTType, mapper, compilation, false);
                     if (vtableAttribute != default)
                     {
                         vtableAttributes.Add(vtableAttribute);
diff --git a/src/Authoring/WinRT.SourceGenerator/DiagnosticUtils.cs b/src/Authoring/WinRT.SourceGenerator/DiagnosticUtils.cs
index 242b0de88..3998c7487 100644
--- a/src/Authoring/WinRT.SourceGenerator/DiagnosticUtils.cs
+++ b/src/Authoring/WinRT.SourceGenerator/DiagnosticUtils.cs
@@ -7,20 +7,22 @@
 using System;
 using WinRT.SourceGenerator;
 
-namespace Generator
+namespace Generator
 {
     public partial class WinRTComponentScanner
     {
-        public WinRTComponentScanner(GeneratorExecutionContext context, string assemblyName)
-        {
+        public WinRTComponentScanner(GeneratorExecutionContext context, string assemblyName)
+        {
             _assemblyName = assemblyName;
             _context = context;
             _flag = false;
+            _typeMapper = new TypeMapper(context.AnalyzerConfigOptions.GlobalOptions.GetUIXamlProjectionsMode());
         }
 
         private readonly string _assemblyName;
         private readonly GeneratorExecutionContext _context;
         private bool _flag;
+        private readonly TypeMapper _typeMapper;
 
         public bool Found() { return _flag; }
 
@@ -31,59 +33,59 @@ public void FindDiagnostics()
         {
             WinRTSyntaxReceiver syntaxReceiver = (WinRTSyntaxReceiver)_context.SyntaxReceiver;
 
-            if (!syntaxReceiver.Declarations.Any())
-            {
+            if (!syntaxReceiver.Declarations.Any())
+            {
                 Report(WinRTRules.NoPublicTypesRule, null);
                 return;
             }
 
-            CheckNamespaces();
-            CheckDeclarations();
-        }
-
-        private void CheckNamespaces()
-        {
+            CheckNamespaces();
+            CheckDeclarations();
+        }
+
+        private void CheckNamespaces()
+        {
             WinRTSyntaxReceiver syntaxReceiver = (WinRTSyntaxReceiver)_context.SyntaxReceiver;
-
-            // Used to check for conflicting namespace names
-            HashSet<string> namespaceNames = new();
-
-            foreach (var @namespace in syntaxReceiver.Namespaces)
-            {
-                var model = _context.Compilation.GetSemanticModel(@namespace.SyntaxTree);
-                var namespaceSymbol = model.GetDeclaredSymbol(@namespace);
-
-                string namespaceString = namespaceSymbol.ToString();
-
-                bool newNamespaceDeclaration = true;
-                // Because modules could have a namespace defined in different places (i.e. defines a partial class)
-                // we can't rely on `Contains` so we manually check that namespace names cannot differ by case only
-                foreach (var usedNamespaceName in namespaceNames)
-                {
-                    if (String.Equals(namespaceString, usedNamespaceName, StringComparison.OrdinalIgnoreCase) &&
-                        !String.Equals(namespaceString, usedNamespaceName, StringComparison.Ordinal))
-                    {
-                        newNamespaceDeclaration = false;
-                        Report(WinRTRules.NamespacesDifferByCase, namespaceSymbol.Locations.First(), namespaceString);
-                    }
-                }
-
-                if (newNamespaceDeclaration)
-                {
-                    namespaceNames.Add(namespaceString);
-                }
-
-                if (IsInvalidNamespace(namespaceSymbol, _assemblyName))
-                {
-                    Report(WinRTRules.DisjointNamespaceRule, namespaceSymbol.Locations.First(), _assemblyName, namespaceString);
-                }
+
+            // Used to check for conflicting namespace names
+            HashSet<string> namespaceNames = new();
+
+            foreach (var @namespace in syntaxReceiver.Namespaces)
+            {
+                var model = _context.Compilation.GetSemanticModel(@namespace.SyntaxTree);
+                var namespaceSymbol = model.GetDeclaredSymbol(@namespace);
+
+                string namespaceString = namespaceSymbol.ToString();
+
+                bool newNamespaceDeclaration = true;
+                // Because modules could have a namespace defined in different places (i.e. defines a partial class)
+                // we can't rely on `Contains` so we manually check that namespace names cannot differ by case only
+                foreach (var usedNamespaceName in namespaceNames)
+                {
+                    if (String.Equals(namespaceString, usedNamespaceName, StringComparison.OrdinalIgnoreCase) &&
+                        !String.Equals(namespaceString, usedNamespaceName, StringComparison.Ordinal))
+                    {
+                        newNamespaceDeclaration = false;
+                        Report(WinRTRules.NamespacesDifferByCase, namespaceSymbol.Locations.First(), namespaceString);
+                    }
+                }
+
+                if (newNamespaceDeclaration)
+                {
+                    namespaceNames.Add(namespaceString);
+                }
+
+                if (IsInvalidNamespace(namespaceSymbol, _assemblyName))
+                {
+                    Report(WinRTRules.DisjointNamespaceRule, namespaceSymbol.Locations.First(), _assemblyName, namespaceString);
+                }
             }
         }
 
-        private void CheckDeclarations()
-        {
-            WinRTSyntaxReceiver syntaxReceiver = (WinRTSyntaxReceiver)_context.SyntaxReceiver;
-
+        private void CheckDeclarations()
+        {
+            WinRTSyntaxReceiver syntaxReceiver = (WinRTSyntaxReceiver)_context.SyntaxReceiver;
+
             foreach (var declaration in syntaxReceiver.Declarations)
             {
                 var model = _context.Compilation.GetSemanticModel(declaration.SyntaxTree);
@@ -91,12 +93,12 @@ private void CheckDeclarations()
 
                 // Check symbol information for whether it is public to properly detect partial types
                 // which can leave out modifier. Also ignore nested types not effectively public
-                if (symbol.DeclaredAccessibility != Accessibility.Public ||
-                    (symbol is ITypeSymbol typeSymbol && !typeSymbol.IsPubliclyAccessible()))
-                {
-                    continue;
-                }
-
+                if (symbol.DeclaredAccessibility != Accessibility.Public ||
+                    (symbol is ITypeSymbol typeSymbol && !typeSymbol.IsPubliclyAccessible()))
+                {
+                    continue;
+                }
+
                 if (declaration is ClassDeclarationSyntax @class)
                 {
                     var classId = @class.Identifier;
@@ -105,7 +107,7 @@ private void CheckDeclarations()
                     var props = @class.DescendantNodes().OfType<PropertyDeclarationSyntax>().Where(IsPublic);
 
                     // filter out methods and properties that will be replaced with our custom type mappings
-                    IgnoreCustomTypeMappings(classSymbol, ref publicMethods, ref props);
+                    IgnoreCustomTypeMappings(classSymbol, _typeMapper, ref publicMethods, ref props);
 
                     if (!classSymbol.IsSealed && !classSymbol.IsStatic)
                     {
@@ -116,112 +118,113 @@ private void CheckDeclarations()
                     HasMultipleConstructorsOfSameArity(@class);
 
                     if (classSymbol.IsGenericType)
-                    {
+                    {
                         Report(WinRTRules.GenericTypeRule, @class.GetLocation(), classId);
                     }
 
                     // check for things in nonWindowsRuntimeInterfaces
-                    ImplementsInvalidInterface(classSymbol, @class);
-
-                    CheckProperties(props, classId);
-
-                    // check types -- todo: check for !valid types
-                    CheckMethods(publicMethods, classId);
-
+                    ImplementsInvalidInterface(classSymbol, @class);
+
+                    CheckProperties(props, classId);
+
+                    // check types -- todo: check for !valid types
+                    CheckMethods(publicMethods, classId);
+
                     CheckInterfaces(model, @class);
                 }
                 else if (declaration is InterfaceDeclarationSyntax @interface)
                 {
                     var interfaceSym = model.GetDeclaredSymbol(@interface);
                     var methods = @interface.DescendantNodes().OfType<MethodDeclarationSyntax>();
-                    var props = @interface.DescendantNodes().OfType<PropertyDeclarationSyntax>().Where(IsPublic);
-
-                    // filter out methods and properties that will be replaced with our custom type mappings
-                    IgnoreCustomTypeMappings(interfaceSym, ref methods, ref props);
-
+                    var props = @interface.DescendantNodes().OfType<PropertyDeclarationSyntax>().Where(IsPublic);
+
+                    // filter out methods and properties that will be replaced with our custom type mappings
+                    IgnoreCustomTypeMappings(interfaceSym, _typeMapper, ref methods, ref props);
+
                     if (interfaceSym.IsGenericType)
                     {
                         Report(WinRTRules.GenericTypeRule, @interface.GetLocation(), @interface.Identifier);
                     }
 
-                    ImplementsInvalidInterface(interfaceSym, @interface);
-
-                    CheckProperties(props, @interface.Identifier);
-
+                    ImplementsInvalidInterface(interfaceSym, @interface);
+
+                    CheckProperties(props, @interface.Identifier);
+
                     CheckMethods(methods, @interface.Identifier);
-                }
-                else if (declaration is StructDeclarationSyntax @struct)
-                {
-                    CheckStructFields(@struct);
-                }
+                }
+                else if (declaration is StructDeclarationSyntax @struct)
+                {
+                    CheckStructFields(@struct);
+                }
             }
-        }
-
-        private void CheckInterfaces(SemanticModel model, ClassDeclarationSyntax @class)
-        {
-            var classId = @class.Identifier;
+        }
+
+        private void CheckInterfaces(SemanticModel model, ClassDeclarationSyntax @class)
+        {
+            var classId = @class.Identifier;
             var classSymbol = model.GetDeclaredSymbol(@class);
-
-            var iWinRTObject = model.Compilation.GetTypeByMetadataName("WinRT.IWinRTObject");
-            // validate that the class correctly implements all its interfaces
-            var methods = classSymbol.GetMembers().OfType<IMethodSymbol>().ToList();
-            foreach (var iface in classSymbol.AllInterfaces)
-            {
-                if (SymbolEqualityComparer.Default.Equals(iface, iWinRTObject))
-                {
-                    continue;
-                }
-                foreach (var member in iface.GetMembers().OfType<IMethodSymbol>())
-                {
-                    var impl = classSymbol.FindImplementationForInterfaceMember(member);
-                    if (impl == null)
-                    {
-                        var explicitIfaceImpl = methods.Where(m => IsMethodImpl(m, member));
-                        if (!explicitIfaceImpl.Any())
-                        {
-                            Report(WinRTRules.UnimplementedInterface, @class.GetLocation(), classId.Text, iface.ToDisplayString(), member.ToDisplayString());
-                        }
-                    }
-                }
-            }
-        }
-
-        private bool IsMethodImpl(IMethodSymbol m, IMethodSymbol interfaceMethod)
-        {
-            if (m.Name != interfaceMethod.Name)
-            {
-                return false;
-            }
-            if (!m.Parameters.SequenceEqual(interfaceMethod.Parameters))
-            {
-                return false;
-            }
-
-            // the return type can be covariant with the interface method's return type (i.e. a sub-type)
-            if (SymEq(m.ReturnType, interfaceMethod.ReturnType) && !m.ReturnType.AllInterfaces.Contains(interfaceMethod.ReturnType, SymbolEqualityComparer.Default))
-            {
-                return false;
-            }
-            return true;
-        }
-
-        private void IgnoreCustomTypeMappings(INamedTypeSymbol typeSymbol,
-            ref IEnumerable<MethodDeclarationSyntax> methods,
+
+            var iWinRTObject = model.Compilation.GetTypeByMetadataName("WinRT.IWinRTObject");
+            // validate that the class correctly implements all its interfaces
+            var methods = classSymbol.GetMembers().OfType<IMethodSymbol>().ToList();
+            foreach (var iface in classSymbol.AllInterfaces)
+            {
+                if (SymbolEqualityComparer.Default.Equals(iface, iWinRTObject))
+                {
+                    continue;
+                }
+                foreach (var member in iface.GetMembers().OfType<IMethodSymbol>())
+                {
+                    var impl = classSymbol.FindImplementationForInterfaceMember(member);
+                    if (impl == null)
+                    {
+                        var explicitIfaceImpl = methods.Where(m => IsMethodImpl(m, member));
+                        if (!explicitIfaceImpl.Any())
+                        {
+                            Report(WinRTRules.UnimplementedInterface, @class.GetLocation(), classId.Text, iface.ToDisplayString(), member.ToDisplayString());
+                        }
+                    }
+                }
+            }
+        }
+
+        private bool IsMethodImpl(IMethodSymbol m, IMethodSymbol interfaceMethod)
+        {
+            if (m.Name != interfaceMethod.Name)
+            {
+                return false;
+            }
+            if (!m.Parameters.SequenceEqual(interfaceMethod.Parameters))
+            {
+                return false;
+            }
+
+            // the return type can be covariant with the interface method's return type (i.e. a sub-type)
+            if (SymEq(m.ReturnType, interfaceMethod.ReturnType) && !m.ReturnType.AllInterfaces.Contains(interfaceMethod.ReturnType, SymbolEqualityComparer.Default))
+            {
+                return false;
+            }
+            return true;
+        }
+
+        private void IgnoreCustomTypeMappings(INamedTypeSymbol typeSymbol,
+            TypeMapper typeMapper,
+            ref IEnumerable<MethodDeclarationSyntax> methods,
             ref IEnumerable<PropertyDeclarationSyntax> properties)
         {
-            string QualifiedName(INamedTypeSymbol sym)
-            {
-                return sym.OriginalDefinition.ContainingNamespace + "." + sym.OriginalDefinition.MetadataName;
+            string QualifiedName(INamedTypeSymbol sym)
+            {
+                return sym.OriginalDefinition.ContainingNamespace + "." + sym.OriginalDefinition.MetadataName;
             }
 
             HashSet<ISymbol> classMethods = new(SymbolEqualityComparer.Default);
 
             foreach (var @interface in typeSymbol.AllInterfaces.
-                        Where(symbol => GeneratorHelper.MappedCSharpTypes.ContainsKey(QualifiedName(symbol)) ||
+                        Where(symbol => typeMapper.HasMappingForType(QualifiedName(symbol)) ||
                                         WinRTTypeWriter.ImplementedInterfacesWithoutMapping.Contains(QualifiedName(symbol))))
             {
                 foreach (var interfaceMember in @interface.GetMembers())
-                {
+                {
                     classMethods.Add(typeSymbol.FindImplementationForInterfaceMember(interfaceMember));
                 }
             }
@@ -276,9 +279,9 @@ private void HasConflictingParameterName(MethodDeclarationSyntax method)
             bool IsInvalidParameterName(ParameterSyntax stx) { return stx.Identifier.Value.Equals(GeneratedReturnValueName); }
 
             var hasInvalidParams = method.ParameterList.Parameters.Any(IsInvalidParameterName);
-            if (hasInvalidParams)
-            {
-                Report(WinRTRules.ParameterNamedValueRule, method.GetLocation(), method.Identifier);
+            if (hasInvalidParams)
+            {
+                Report(WinRTRules.ParameterNamedValueRule, method.GetLocation(), method.Identifier);
             }
         }
 
@@ -307,7 +310,7 @@ private void CheckMethods(IEnumerable<MethodDeclarationSyntax> methodDeclaration
                 foreach (var arg in methodSym.Parameters)
                 {
                     ReportIfInvalidType(arg.Type, method.GetLocation(), method.Identifier, typeId);
-                }
+                }
             }
             /* Finishes up the work started by `CheckOverloadAttributes` */
             foreach (var thing in overloadsWithoutAttributeMap)
@@ -326,9 +329,9 @@ private void CheckProperties(IEnumerable<PropertyDeclarationSyntax> props, Synta
                 var propSym = GetModel(prop.SyntaxTree).GetDeclaredSymbol(prop);
                 var loc = prop.GetLocation();
 
-                if (propSym.GetMethod == null || !propSym.GetMethod.DeclaredAccessibility.Equals(Accessibility.Public))
-                {
-                    Report(WinRTRules.PrivateGetterRule, loc, prop.Identifier);
+                if (propSym.GetMethod == null || !propSym.GetMethod.DeclaredAccessibility.Equals(Accessibility.Public))
+                {
+                    Report(WinRTRules.PrivateGetterRule, loc, prop.Identifier);
                 }
 
                 ReportIfInvalidType(propSym.Type, loc, prop.Identifier, typeId);
@@ -345,12 +348,12 @@ private void CheckStructFields(StructDeclarationSyntax @struct)
         {
             // delegates not allowed 
             if (@struct.DescendantNodes().OfType<DelegateDeclarationSyntax>().Any())
-            {
+            {
                 Report(WinRTRules.StructHasInvalidFieldRule, @struct.GetLocation(), @struct.Identifier, SimplifySyntaxTypeString(typeof(DelegateDeclarationSyntax).Name));
             }
             // methods not allowed
             if (@struct.DescendantNodes().OfType<MethodDeclarationSyntax>().Any())
-            {
+            {
                 Report(WinRTRules.StructHasInvalidFieldRule, @struct.GetLocation(), @struct.Identifier, SimplifySyntaxTypeString(typeof(MethodDeclarationSyntax).Name));
             }
 
@@ -358,16 +361,16 @@ private void CheckStructFields(StructDeclarationSyntax @struct)
 
             // constructors not allowed 
             if (structSym.Constructors.Length > 1)
-            {
+            {
                 Report(WinRTRules.StructHasInvalidFieldRule, @struct.GetLocation(), @struct.Identifier, SimplifySyntaxTypeString(typeof(ConstructorDeclarationSyntax).Name));
             }
 
             var fields = @struct.DescendantNodes().OfType<FieldDeclarationSyntax>();
-            foreach (var field in fields)
+            foreach (var field in fields)
             {
                 // all fields must be public
                 if (!IsPublic(field))
-                {
+                {
                     Report(WinRTRules.StructHasPrivateFieldRule, field.GetLocation(), @struct.Identifier);
                 }
 
@@ -381,14 +384,14 @@ private void CheckStructFields(StructDeclarationSyntax @struct)
                 {
                     IFieldSymbol varFieldSym = (IFieldSymbol)GetModel(variable.SyntaxTree).GetDeclaredSymbol(variable);
 
-                    if (ValidStructFieldTypes.Contains(varFieldSym.Type.SpecialType) ||
+                    if (ValidStructFieldTypes.Contains(varFieldSym.Type.SpecialType) ||
                         varFieldSym.Type.TypeKind == TypeKind.Struct ||
                         varFieldSym.Type.TypeKind == TypeKind.Enum)
                     {
                         break;
                     }
                     else
-                    {
+                    {
                         Report(WinRTRules.StructHasInvalidFieldRule, variable.GetLocation(), @struct.Identifier, varFieldSym.Name);
                     }
                 }
@@ -406,23 +409,23 @@ private void CheckStructFields(StructDeclarationSyntax @struct)
         /// <param name="namespace">the authored namespace to check</param><param name="assemblyName">the name of the component/winmd</param>
         /// <returns>True iff namespace is disjoint from the assembly name</returns>
         private bool IsInvalidNamespace(INamespaceSymbol @namespace, string assemblyName)
-        {
-            if (string.CompareOrdinal(@namespace.ToString(), assemblyName) == 0)
-            {
-                return false;
-            }
-
+        {
+            if (string.CompareOrdinal(@namespace.ToString(), assemblyName) == 0)
+            {
+                return false;
+            }
+
             var topLevel = @namespace;
             while (!topLevel.ContainingNamespace.IsGlobalNamespace)
-            {
-                if (string.CompareOrdinal(topLevel.ToString(), assemblyName) == 0)
-                {
-                    return false;
+            {
+                if (string.CompareOrdinal(topLevel.ToString(), assemblyName) == 0)
+                {
+                    return false;
                 }
                 topLevel = topLevel.ContainingNamespace;
-            }
-
-            return string.CompareOrdinal(topLevel.ToString(), assemblyName) != 0;
+            }
+
+            return string.CompareOrdinal(topLevel.ToString(), assemblyName) != 0;
         }
 
         ///<summary>Array types can only be one dimensional and not System.Array, 
@@ -430,22 +433,22 @@ private bool IsInvalidNamespace(INamespaceSymbol @namespace, string assemblyName
         ///<param name="typeSymbol">The type to check</param><param name="loc">where the type is</param>
         ///<param name="memberId">The method or property with this type in its signature</param>
         /// <param name="typeId">the type this member (method/prop) lives in</param>
-        private void ReportIfInvalidType(ITypeSymbol typeSymbol, Location loc, SyntaxToken memberId, SyntaxToken typeId)
+        private void ReportIfInvalidType(ITypeSymbol typeSymbol, Location loc, SyntaxToken memberId, SyntaxToken typeId)
         {
             // If it's of the form int[], it has to be one dimensional
-            if (typeSymbol.TypeKind == TypeKind.Array)
+            if (typeSymbol.TypeKind == TypeKind.Array)
             {
                 IArrayTypeSymbol arrTypeSym = (IArrayTypeSymbol)typeSymbol;
 
                 // [,,]?
-                if (arrTypeSym.Rank > 1)
-                {
+                if (arrTypeSym.Rank > 1)
+                {
                     Report(WinRTRules.MultiDimensionalArrayRule, loc, memberId, typeId);
                     return;
-                }
-                // [][]?
-                if (arrTypeSym.ElementType.TypeKind == TypeKind.Array)
-                {
+                }
+                // [][]?
+                if (arrTypeSym.ElementType.TypeKind == TypeKind.Array)
+                {
                     Report(WinRTRules.JaggedArrayRule, loc, memberId, typeId);
                     return;
                 }
@@ -453,7 +456,7 @@ private void ReportIfInvalidType(ITypeSymbol typeSymbol, Location loc, SyntaxTok
 
             // NotValidTypes is an array of types that don't exist in Windows Runtime, so can't be passed between functions in Windows Runtime
             foreach (var typeName in NotValidTypes)
-            {
+            {
                 var notValidTypeSym = GetTypeByMetadataName(typeName);
                 if (SymEq(typeSymbol.OriginalDefinition, notValidTypeSym))
                 {
@@ -467,21 +470,21 @@ private void ReportIfInvalidType(ITypeSymbol typeSymbol, Location loc, SyntaxTok
             if (typeSymbol.ContainingNamespace != null && !typeSymbol.ContainingNamespace.IsGlobalNamespace)
             {
                 // ContainingNamespace for Enumerable is just System, but we need System.Linq which is the ContainingSymbol
-                qualifiedName += typeSymbol.ContainingSymbol + ".";
+                qualifiedName += typeSymbol.ContainingSymbol + ".";
             }
             // instead of TypeName<int>, TypeName`1
             qualifiedName += typeSymbol.MetadataName;
 
             // GetTypeByMetadataName fails on "System.Linq.Enumerable" & "System.Collections.ObjectModel.ReadOnlyDictionary`2"
             // Would be fixed by issue #678 on the dotnet/roslyn-sdk repo
-            foreach (var notValidType in WIPNotValidTypes)
+            foreach (var notValidType in WIPNotValidTypes)
             {
                 if (qualifiedName == notValidType)
-                {
+                {
                     Report(WinRTRules.UnsupportedTypeRule, loc, memberId, notValidType, SuggestType(notValidType));
                     return;
                 }
             }
-        }
+        }
     }
 }
diff --git a/src/Authoring/WinRT.SourceGenerator/Generator.cs b/src/Authoring/WinRT.SourceGenerator/Generator.cs
index 5f5dd4314..370e2c437 100644
--- a/src/Authoring/WinRT.SourceGenerator/Generator.cs
+++ b/src/Authoring/WinRT.SourceGenerator/Generator.cs
@@ -1,4 +1,4 @@
-using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Text;
@@ -21,11 +21,14 @@ public class ComponentGenerator
         private Logger Logger { get; }
         private readonly GeneratorExecutionContext context;
         private string tempFolder;
+        private readonly TypeMapper mapper;
 
         public ComponentGenerator(GeneratorExecutionContext context)
         {
             this.context = context;
             Logger = new Logger(context);
+            mapper = new(context.AnalyzerConfigOptions.GlobalOptions.GetUIXamlProjectionsMode());
+            // TODO-WuxMux: output a module initializer that validates the MUX/WUX projection mode to ensure that things don't get out of sync.
         }
 
         [SuppressMessage("MicrosoftCodeAnalysisCorrectness", "RS1035", Justification = "We need to do file IO to invoke the 'cswinrt' tool.")]
@@ -158,7 +161,8 @@ public void Generate()
                     assembly,
                     version,
                     metadataBuilder,
-                    Logger);
+                    Logger,
+                    mapper);
 
                 WinRTSyntaxReceiver syntaxReceiver = (WinRTSyntaxReceiver)context.SyntaxReceiver;
                 Logger.Log("Found " + syntaxReceiver.Declarations.Count + " types");
diff --git a/src/Authoring/WinRT.SourceGenerator/Helper.cs b/src/Authoring/WinRT.SourceGenerator/Helper.cs
index 0f72bfbb6..d06a1ff1c 100644
--- a/src/Authoring/WinRT.SourceGenerator/Helper.cs
+++ b/src/Authoring/WinRT.SourceGenerator/Helper.cs
@@ -231,12 +231,12 @@ private static bool IsFundamentalType(ISymbol type)
             return type.ToDisplayString() == "System.Guid";
         }
 
-        public static bool IsWinRTType(ISymbol type)
+        public static bool IsWinRTType(ISymbol type, TypeMapper mapper)
         {
-            return IsWinRTType(type, null);
+            return IsWinRTType(type, null, mapper);
         }
 
-        public static bool IsWinRTType(ISymbol type, Func<ISymbol, bool> isAuthoringWinRTType)
+        public static bool IsWinRTType(ISymbol type, Func<ISymbol, TypeMapper, bool> isAuthoringWinRTType, TypeMapper mapper)
         {
             bool isProjectedType = type.GetAttributes().
                 Any(attribute => string.CompareOrdinal(attribute.AttributeClass.Name, "WindowsRuntimeTypeAttribute") == 0) ||
@@ -244,21 +244,21 @@ public static bool IsWinRTType(ISymbol type, Func<ISymbol, bool> isAuthoringWinR
 
             if (!isProjectedType & type.ContainingNamespace != null)
             {
-                isProjectedType = MappedCSharpTypes.ContainsKey(string.Join(".", type.ContainingNamespace.ToDisplayString(), type.MetadataName));
+                isProjectedType = mapper.HasMappingForType(string.Join(".", type.ContainingNamespace.ToDisplayString(), type.MetadataName));
             }
 
             // Ensure all generic parameters are WinRT types.
             if (isProjectedType && type is INamedTypeSymbol namedType && namedType.IsGenericType && !namedType.IsDefinition)
             {
                 isProjectedType = namedType.TypeArguments.All(t => 
-                    IsWinRTType(t, isAuthoringWinRTType) || 
-                    (isAuthoringWinRTType != null && isAuthoringWinRTType(t)));
+                    IsWinRTType(t, isAuthoringWinRTType, mapper) || 
+                    (isAuthoringWinRTType != null && isAuthoringWinRTType(t, mapper)));
             }
 
             return isProjectedType;
         }
 
-        public static bool IsWinRTType(ISymbol type, ITypeSymbol winrtRuntimeTypeAttribute, bool isComponentProject, IAssemblySymbol currentAssembly)
+        public static bool IsWinRTType(ISymbol type, ITypeSymbol winrtRuntimeTypeAttribute, TypeMapper mapper, bool isComponentProject, IAssemblySymbol currentAssembly)
         {
             if (IsFundamentalType(type))
             {
@@ -277,7 +277,7 @@ public static bool IsWinRTType(ISymbol type, ITypeSymbol winrtRuntimeTypeAttribu
             bool isProjectedType = HasAttributeWithType(type, winrtRuntimeTypeAttribute);
             if (!isProjectedType & type.ContainingNamespace != null)
             {
-                isProjectedType = MappedCSharpTypes.ContainsKey(string.Join(".", type.ContainingNamespace.ToDisplayString(), type.MetadataName));
+                isProjectedType = mapper.HasMappingForType(string.Join(".", type.ContainingNamespace.ToDisplayString(), type.MetadataName));
             }
 
             // Ensure all generic parameters are WinRT types.
@@ -286,7 +286,7 @@ type is INamedTypeSymbol namedType &&
                 namedType.IsGenericType && 
                 !namedType.IsDefinition)
             {
-                isProjectedType = namedType.TypeArguments.All(t => IsWinRTType(t, winrtRuntimeTypeAttribute, isComponentProject, currentAssembly));
+                isProjectedType = namedType.TypeArguments.All(t => IsWinRTType(t, winrtRuntimeTypeAttribute, mapper, isComponentProject, currentAssembly));
             }
 
             return isProjectedType;
@@ -341,14 +341,14 @@ public static bool IsInternalInterfaceFromReferences(INamedTypeSymbol iface, IAs
         // and is used by a WinRT interface. For instance, List<T> where T is a generic.
         // If the generic isn't used by any WinRT interface, this returns false as for
         // instance, we can still generate the vtable attribute for it.
-        public static bool HasNonInstantiatedWinRTGeneric(ITypeSymbol symbol)
+        public static bool HasNonInstantiatedWinRTGeneric(ITypeSymbol symbol, TypeMapper mapper)
         {
             return symbol is INamedTypeSymbol namedType && 
                 (IsArgumentTypeParameter(namedType) || 
                  (namedType.TypeArguments.Any(IsArgumentTypeParameter) && 
                   namedType.AllInterfaces.Any(iface => iface.TypeArguments.Any(IsArgumentTypeParameter) && 
                   // Checks if without the non-instantiated generic, whether it would be a WinRT type.
-                  IsWinRTType(iface.OriginalDefinition, null))));
+                  IsWinRTType(iface.OriginalDefinition, null, mapper))));
 
             static bool IsArgumentTypeParameter(ITypeSymbol argument)
             {
@@ -411,14 +411,14 @@ public static bool HasAttributeWithType(ISymbol symbol, ITypeSymbol attributeTyp
             return false;
         }
 
-        public static Func<ISymbol, bool> IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(Compilation compilation)
+        public static Func<ISymbol, TypeMapper, bool> IsWinRTTypeWithPotentialAuthoringComponentTypesFunc(Compilation compilation)
         {
             var winrtTypeAttribute = compilation.GetTypeByMetadataName("WinRT.WindowsRuntimeTypeAttribute");
             return IsWinRTTypeHelper;
 
-            bool IsWinRTTypeHelper(ISymbol type)
+            bool IsWinRTTypeHelper(ISymbol type, TypeMapper typeMapper)
             {
-                return IsWinRTType(type, winrtTypeAttribute, true, compilation.Assembly);
+                return IsWinRTType(type, winrtTypeAttribute, typeMapper, true, compilation.Assembly);
             }
         }
 
@@ -452,7 +452,7 @@ private static string GetAbiTypeForFundamentalType(ISymbol type)
             return type.ToDisplayString();
         }
 
-        public static bool IsBlittableValueType(ITypeSymbol type)
+        public static bool IsBlittableValueType(ITypeSymbol type, TypeMapper typeMapper)
         {
             if (!type.IsValueType)
             {
@@ -484,9 +484,9 @@ public static bool IsBlittableValueType(ITypeSymbol type)
             if (type.ContainingNamespace != null)
             {
                 string customTypeMapKey = string.Join(".", type.ContainingNamespace.ToDisplayString(), type.MetadataName);
-                if (MappedCSharpTypes.ContainsKey(customTypeMapKey))
+                if (typeMapper.HasMappingForType(customTypeMapKey))
                 {
-                    return MappedCSharpTypes[customTypeMapKey].IsBlittable();
+                    return typeMapper.GetMappedType(customTypeMapKey).IsBlittable();
                 }
             }
 
@@ -501,7 +501,7 @@ public static bool IsBlittableValueType(ITypeSymbol type)
                 {
                     if (typeMember is IFieldSymbol field &&
                         !field.IsStatic &&
-                        !IsBlittableValueType(field.Type))
+                        !IsBlittableValueType(field.Type, typeMapper))
                     {
                         return false;
                     }
@@ -510,7 +510,7 @@ public static bool IsBlittableValueType(ITypeSymbol type)
             return true;
         }
 
-        public static string GetAbiType(ITypeSymbol type)
+        public static string GetAbiType(ITypeSymbol type, TypeMapper mapper)
         {
             if (IsFundamentalType(type))
             {
@@ -530,13 +530,13 @@ public static string GetAbiType(ITypeSymbol type)
             if (type.IsValueType)
             {
                 string customTypeMapKey = string.Join(".", type.ContainingNamespace.ToDisplayString(), type.MetadataName);
-                if (MappedCSharpTypes.ContainsKey(customTypeMapKey))
+                if (mapper.HasMappingForType(customTypeMapKey))
                 {
-                    string prefix = MappedCSharpTypes[customTypeMapKey].IsBlittable() ? "" : "ABI.";
+                    string prefix = mapper.GetMappedType(customTypeMapKey).IsBlittable() ? "" : "ABI.";
                     return prefix + typeStr;
                 }
 
-                if (!IsBlittableValueType(type))
+                if (!IsBlittableValueType(type, mapper))
                 {
                     var winrtHelperAttribute = type.GetAttributes().
                         Where(attribute => string.CompareOrdinal(attribute.AttributeClass.Name, "WindowsRuntimeHelperTypeAttribute") == 0).
diff --git a/src/Authoring/WinRT.SourceGenerator/Properties/launchSettings.json b/src/Authoring/WinRT.SourceGenerator/Properties/launchSettings.json
new file mode 100644
index 000000000..ef608ed3b
--- /dev/null
+++ b/src/Authoring/WinRT.SourceGenerator/Properties/launchSettings.json
@@ -0,0 +1,8 @@
+{
+  "profiles": {
+    "WinRT.SourceGenerator": {
+      "commandName": "DebugRoslynComponent",
+      "targetProject": "..\\..\\Projections\\Windows\\Windows.csproj"
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/Authoring/WinRT.SourceGenerator/TypeMapper.cs b/src/Authoring/WinRT.SourceGenerator/TypeMapper.cs
new file mode 100644
index 000000000..bfec7684a
--- /dev/null
+++ b/src/Authoring/WinRT.SourceGenerator/TypeMapper.cs
@@ -0,0 +1,125 @@
+using Microsoft.CodeAnalysis;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using static Generator.GeneratorHelper;
+
+namespace Generator
+{
+    internal sealed class TypeMapper
+    {
+        private readonly Dictionary<string, MappedType> typeMapping;
+
+        // Based on whether System.Type is used in an attribute declaration or elsewhere, we need to choose the correct custom mapping
+        // as attributes don't use the TypeName mapping.
+        private static (string, string, string, bool, bool) GetSystemTypeCustomMapping(ISymbol containingSymbol)
+        {
+            bool isDefinedInAttribute =
+                containingSymbol != null &&
+                    string.CompareOrdinal((containingSymbol as INamedTypeSymbol).BaseType?.ToString(), "System.Attribute") == 0;
+            return isDefinedInAttribute ?
+                ("System", "Type", "mscorlib", true, false) :
+                ("Windows.UI.Xaml.Interop", "TypeName", "Windows.Foundation.UniversalApiContract", false, true);
+        }
+
+        public TypeMapper(UIXamlProjectionsMode xamlMode)
+        {
+            // This should be in sync with the reverse mapping from WinRT.Runtime/Projections.cs and cswinrt/helpers.h.
+            if (xamlMode == UIXamlProjectionsMode.WindowsUIXaml)
+            {
+                typeMapping = new(StringComparer.Ordinal)
+                {
+                    { "System.DateTimeOffset", new MappedType("Windows.Foundation", "DateTime", "Windows.Foundation.FoundationContract", true, false) },
+                    { "System.Exception", new MappedType("Windows.Foundation", "HResult", "Windows.Foundation.FoundationContract", true, false) },
+                    { "System.EventHandler`1", new MappedType("Windows.Foundation", "EventHandler`1", "Windows.Foundation.FoundationContract") },
+                    { "System.FlagsAttribute", new MappedType("System", "FlagsAttribute", "mscorlib" ) },
+                    { "System.IDisposable", new MappedType("Windows.Foundation", "IClosable", "Windows.Foundation.FoundationContract") },
+                    { "System.Nullable`1", new MappedType("Windows.Foundation", "IReference`1", "Windows.Foundation.FoundationContract" ) },
+                    { "System.Object", new MappedType("System", "Object", "mscorlib" ) },
+                    { "System.TimeSpan", new MappedType("Windows.Foundation", "TimeSpan", "Windows.Foundation.FoundationContract", true, false) },
+                    { "System.Uri", new MappedType("Windows.Foundation", "Uri", "Windows.Foundation.FoundationContract") },
+                    { "System.ComponentModel.INotifyPropertyChanged", new MappedType("Windows.UI.Xaml.Data", "INotifyPropertyChanged", "Windows.UI.Xaml") },
+                    { "System.ComponentModel.PropertyChangedEventArgs", new MappedType("Windows.UI.Xaml.Data", "PropertyChangedEventArgs", "Windows.UI.Xaml") },
+                    { "System.ComponentModel.PropertyChangedEventHandler", new MappedType("Windows.UI.Xaml.Data", "PropertyChangedEventHandler", "Windows.UI.Xaml") },
+                    { "System.Windows.Input.ICommand", new MappedType("Windows.UI.Xaml.Input", "ICommand", "Windows.UI.Xaml") },
+                    { "System.Collections.IEnumerable", new MappedType("Windows.UI.Xaml.Interop", "IBindableIterable", "Windows.UI.Xaml") },
+                    { "System.Collections.IList", new MappedType("Windows.UI.Xaml.Interop", "IBindableVector", "Windows.UI.Xaml") },
+                    { "System.Collections.Specialized.INotifyCollectionChanged", new MappedType("Windows.UI.Xaml.Interop", "INotifyCollectionChanged", "Windows.UI.Xaml") },
+                    { "System.Collections.Specialized.NotifyCollectionChangedAction", new MappedType("Windows.UI.Xaml.Interop", "NotifyCollectionChangedAction", "Windows.UI.Xaml") },
+                    { "System.Collections.Specialized.NotifyCollectionChangedEventArgs", new MappedType("Windows.UI.Xaml.Interop", "NotifyCollectionChangedEventArgs", "Windows.UI.Xaml") },
+                    { "System.Collections.Specialized.NotifyCollectionChangedEventHandler", new MappedType("Windows.UI.Xaml.Interop", "NotifyCollectionChangedEventHandler", "Windows.UI.Xaml") },
+                    { "WinRT.EventRegistrationToken", new MappedType("Windows.Foundation", "EventRegistrationToken", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.AttributeTargets", new MappedType("Windows.Foundation.Metadata", "AttributeTargets", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.AttributeUsageAttribute", new MappedType("Windows.Foundation.Metadata", "AttributeUsageAttribute", "Windows.Foundation.FoundationContract") },
+                    { "System.Numerics.Matrix3x2", new MappedType("Windows.Foundation.Numerics", "Matrix3x2", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Matrix4x4", new MappedType("Windows.Foundation.Numerics", "Matrix4x4", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Plane", new MappedType("Windows.Foundation.Numerics", "Plane", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Quaternion", new MappedType("Windows.Foundation.Numerics", "Quaternion", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Vector2", new MappedType("Windows.Foundation.Numerics", "Vector2", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Vector3", new MappedType("Windows.Foundation.Numerics", "Vector3", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Vector4", new MappedType("Windows.Foundation.Numerics", "Vector4", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Type", new MappedType(GetSystemTypeCustomMapping) },
+                    { "System.Collections.Generic.IEnumerable`1", new MappedType("Windows.Foundation.Collections", "IIterable`1", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IEnumerator`1", new MappedType("Windows.Foundation.Collections", "IIterator`1", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.KeyValuePair`2", new MappedType("Windows.Foundation.Collections", "IKeyValuePair`2", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IReadOnlyDictionary`2", new MappedType("Windows.Foundation.Collections", "IMapView`2", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IDictionary`2", new MappedType("Windows.Foundation.Collections", "IMap`2", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IReadOnlyList`1", new MappedType("Windows.Foundation.Collections", "IVectorView`1", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IList`1", new MappedType("Windows.Foundation.Collections", "IVector`1", "Windows.Foundation.FoundationContract") },
+                    { "Windows.UI.Color", new MappedType("Windows.UI", "Color", "Windows.Foundation.UniversalApiContract", true, true) },
+                };
+            }
+            else
+            {
+                typeMapping = new(StringComparer.Ordinal)
+                {
+                    { "System.DateTimeOffset", new MappedType("Windows.Foundation", "DateTime", "Windows.Foundation.FoundationContract", true, false) },
+                    { "System.Exception", new MappedType("Windows.Foundation", "HResult", "Windows.Foundation.FoundationContract", true, false) },
+                    { "System.EventHandler`1", new MappedType("Windows.Foundation", "EventHandler`1", "Windows.Foundation.FoundationContract") },
+                    { "System.FlagsAttribute", new MappedType("System", "FlagsAttribute", "mscorlib" ) },
+                    { "System.IDisposable", new MappedType("Windows.Foundation", "IClosable", "Windows.Foundation.FoundationContract") },
+                    { "System.IServiceProvider", new MappedType("Microsoft.UI.Xaml", "IXamlServiceProvider", "Microsoft.UI") },
+                    { "System.Nullable`1", new MappedType("Windows.Foundation", "IReference`1", "Windows.Foundation.FoundationContract" ) },
+                    { "System.Object", new MappedType("System", "Object", "mscorlib" ) },
+                    { "System.TimeSpan", new MappedType("Windows.Foundation", "TimeSpan", "Windows.Foundation.FoundationContract", true, false) },
+                    { "System.Uri", new MappedType("Windows.Foundation", "Uri", "Windows.Foundation.FoundationContract") },
+                    { "System.ComponentModel.DataErrorsChangedEventArgs", new MappedType("Microsoft.UI.Xaml.Data", "DataErrorsChangedEventArgs", "Microsoft.UI") },
+                    { "System.ComponentModel.INotifyDataErrorInfo", new MappedType("Microsoft.UI.Xaml.Data", "INotifyDataErrorInfo", "Microsoft.UI") },
+                    { "System.ComponentModel.INotifyPropertyChanged", new MappedType("Microsoft.UI.Xaml.Data", "INotifyPropertyChanged", "Microsoft.UI") },
+                    { "System.ComponentModel.PropertyChangedEventArgs", new MappedType("Microsoft.UI.Xaml.Data", "PropertyChangedEventArgs", "Microsoft.UI") },
+                    { "System.ComponentModel.PropertyChangedEventHandler", new MappedType("Microsoft.UI.Xaml.Data", "PropertyChangedEventHandler", "Microsoft.UI") },
+                    { "System.Windows.Input.ICommand", new MappedType("Microsoft.UI.Xaml.Input", "ICommand", "Microsoft.UI") },
+                    { "System.Collections.IEnumerable", new MappedType("Microsoft.UI.Xaml.Interop", "IBindableIterable", "Microsoft.UI") },
+                    { "System.Collections.IList", new MappedType("Microsoft.UI.Xaml.Interop", "IBindableVector", "Microsoft.UI") },
+                    { "System.Collections.Specialized.INotifyCollectionChanged", new MappedType("Microsoft.UI.Xaml.Interop", "INotifyCollectionChanged", "Microsoft.UI") },
+                    { "System.Collections.Specialized.NotifyCollectionChangedAction", new MappedType("Microsoft.UI.Xaml.Interop", "NotifyCollectionChangedAction", "Microsoft.UI") },
+                    { "System.Collections.Specialized.NotifyCollectionChangedEventArgs", new MappedType("Microsoft.UI.Xaml.Interop", "NotifyCollectionChangedEventArgs", "Microsoft.UI") },
+                    { "System.Collections.Specialized.NotifyCollectionChangedEventHandler", new MappedType("Microsoft.UI.Xaml.Interop", "NotifyCollectionChangedEventHandler", "Microsoft.UI") },
+                    { "WinRT.EventRegistrationToken", new MappedType("Windows.Foundation", "EventRegistrationToken", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.AttributeTargets", new MappedType("Windows.Foundation.Metadata", "AttributeTargets", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.AttributeUsageAttribute", new MappedType("Windows.Foundation.Metadata", "AttributeUsageAttribute", "Windows.Foundation.FoundationContract") },
+                    { "System.Numerics.Matrix3x2", new MappedType("Windows.Foundation.Numerics", "Matrix3x2", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Matrix4x4", new MappedType("Windows.Foundation.Numerics", "Matrix4x4", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Plane", new MappedType("Windows.Foundation.Numerics", "Plane", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Quaternion", new MappedType("Windows.Foundation.Numerics", "Quaternion", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Vector2", new MappedType("Windows.Foundation.Numerics", "Vector2", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Vector3", new MappedType("Windows.Foundation.Numerics", "Vector3", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Numerics.Vector4", new MappedType("Windows.Foundation.Numerics", "Vector4", "Windows.Foundation.FoundationContract", true, true) },
+                    { "System.Type", new MappedType(GetSystemTypeCustomMapping) },
+                    { "System.Collections.Generic.IEnumerable`1", new MappedType("Windows.Foundation.Collections", "IIterable`1", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IEnumerator`1", new MappedType("Windows.Foundation.Collections", "IIterator`1", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.KeyValuePair`2", new MappedType("Windows.Foundation.Collections", "IKeyValuePair`2", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IReadOnlyDictionary`2", new MappedType("Windows.Foundation.Collections", "IMapView`2", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IDictionary`2", new MappedType("Windows.Foundation.Collections", "IMap`2", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IReadOnlyList`1", new MappedType("Windows.Foundation.Collections", "IVectorView`1", "Windows.Foundation.FoundationContract") },
+                    { "System.Collections.Generic.IList`1", new MappedType("Windows.Foundation.Collections", "IVector`1", "Windows.Foundation.FoundationContract") },
+                    { "Windows.UI.Color", new MappedType("Windows.UI", "Color", "Windows.Foundation.UniversalApiContract", true, true) },
+                };
+            }
+        }
+
+        public bool HasMappingForType(string typeName) => typeMapping.ContainsKey(typeName);
+
+        public MappedType GetMappedType(string typeName) => typeMapping[typeName];
+    }
+}
diff --git a/src/Authoring/WinRT.SourceGenerator/UIXamlProjectionsMode.cs b/src/Authoring/WinRT.SourceGenerator/UIXamlProjectionsMode.cs
new file mode 100644
index 000000000..1bf4cc329
--- /dev/null
+++ b/src/Authoring/WinRT.SourceGenerator/UIXamlProjectionsMode.cs
@@ -0,0 +1,26 @@
+using Microsoft.CodeAnalysis.Diagnostics;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Generator
+{
+    internal enum UIXamlProjectionsMode
+    {
+        MicrosoftUIXaml,
+        WindowsUIXaml,
+    }
+
+    internal static class OptionsHelper
+    {
+        public static UIXamlProjectionsMode GetUIXamlProjectionsMode(this AnalyzerConfigOptions options)
+        {
+            if (options.TryGetValue("build_property.CsWinRTUIXamlProjections", out var value) && Enum.TryParse<UIXamlProjectionsMode>(value, out UIXamlProjectionsMode mode))
+            {
+                return mode;
+            }
+
+            return UIXamlProjectionsMode.MicrosoftUIXaml;
+        }
+    }
+}
diff --git a/src/Authoring/WinRT.SourceGenerator/WinRT.SourceGenerator.csproj b/src/Authoring/WinRT.SourceGenerator/WinRT.SourceGenerator.csproj
index 66e04a780..357e76314 100644
--- a/src/Authoring/WinRT.SourceGenerator/WinRT.SourceGenerator.csproj
+++ b/src/Authoring/WinRT.SourceGenerator/WinRT.SourceGenerator.csproj
@@ -17,6 +17,7 @@
     <Copyright>Copyright (c) Microsoft Corporation. All rights reserved.</Copyright>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>$(SolutionDir)WinRT.Runtime\key.snk</AssemblyOriginatorKeyFile>
+    <IsRoslynComponent>true</IsRoslynComponent>
     <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
   </PropertyGroup>
 
@@ -31,18 +32,18 @@
     <AdditionalFiles Include="AnalyzerReleases.Shipped.md" />
     <AdditionalFiles Include="AnalyzerReleases.Unshipped.md" />
   </ItemGroup>
-  <ItemGroup>
-    <Compile Update="CsWinRTDiagnosticStrings.Designer.cs">
-      <DesignTime>True</DesignTime>
-      <AutoGen>True</AutoGen>
-      <DependentUpon>CsWinRTDiagnosticStrings.resx</DependentUpon>
-    </Compile>
+  <ItemGroup>
+    <Compile Update="CsWinRTDiagnosticStrings.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>CsWinRTDiagnosticStrings.resx</DependentUpon>
+    </Compile>
   </ItemGroup>
-  <ItemGroup>
-    <EmbeddedResource Update="CsWinRTDiagnosticStrings.resx">
-      <Generator>ResXFileCodeGenerator</Generator>
-      <LastGenOutput>CsWinRTDiagnosticStrings.Designer.cs</LastGenOutput>
-    </EmbeddedResource>
+  <ItemGroup>
+    <EmbeddedResource Update="CsWinRTDiagnosticStrings.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>CsWinRTDiagnosticStrings.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
   </ItemGroup>
 
 </Project>
diff --git a/src/Authoring/WinRT.SourceGenerator/WinRTAotCodeFixer.cs b/src/Authoring/WinRT.SourceGenerator/WinRTAotCodeFixer.cs
index ed2c31bc1..f0f009a15 100644
--- a/src/Authoring/WinRT.SourceGenerator/WinRTAotCodeFixer.cs
+++ b/src/Authoring/WinRT.SourceGenerator/WinRTAotCodeFixer.cs
@@ -42,6 +42,8 @@ public override void Initialize(AnalysisContext context)
                     return;
                 }
 
+                var typeMapper = new TypeMapper(context.Options.AnalyzerConfigOptionsProvider.GlobalOptions.GetUIXamlProjectionsMode());
+
                 context.RegisterSymbolAction(context =>
                 {
                     // Filter to classes that can be passed as objects.
@@ -53,13 +55,13 @@ public override void Initialize(AnalysisContext context)
                         // Make sure this is a class that we would generate the WinRTExposedType attribute on
                         // and that it isn't already partial.
                         if (!GeneratorHelper.IsPartial(namedType) &&
-                            !GeneratorHelper.IsWinRTType(namedType, winrtTypeAttribute, isComponentProject, context.Compilation.Assembly) &&
-                            !GeneratorHelper.HasNonInstantiatedWinRTGeneric(namedType) &&
+                            !GeneratorHelper.IsWinRTType(namedType, winrtTypeAttribute, typeMapper, isComponentProject, context.Compilation.Assembly) &&
+                            !GeneratorHelper.HasNonInstantiatedWinRTGeneric(namedType, typeMapper) &&
                             !GeneratorHelper.HasAttributeWithType(namedType, winrtExposedTypeAttribute))
                         {
                             foreach (var iface in namedType.AllInterfaces)
                             {
-                                if (GeneratorHelper.IsWinRTType(iface, winrtTypeAttribute, isComponentProject, context.Compilation.Assembly))
+                                if (GeneratorHelper.IsWinRTType(iface, winrtTypeAttribute, typeMapper, isComponentProject, context.Compilation.Assembly))
                                 {
                                     context.ReportDiagnostic(Diagnostic.Create(WinRTRules.ClassNotAotCompatible, namedType.Locations[0], namedType.Name));
                                     return;
diff --git a/src/Authoring/WinRT.SourceGenerator/WinRTTypeWriter.cs b/src/Authoring/WinRT.SourceGenerator/WinRTTypeWriter.cs
index 5143a1bf5..4154f62a9 100644
--- a/src/Authoring/WinRT.SourceGenerator/WinRTTypeWriter.cs
+++ b/src/Authoring/WinRT.SourceGenerator/WinRTTypeWriter.cs
@@ -265,7 +265,7 @@ class WinRTTypeWriter : CSharpSyntaxWalker
         private readonly Dictionary<string, TypeReferenceHandle> typeReferenceMapping;
         private readonly Dictionary<string, EntityHandle> assemblyReferenceMapping;
         private readonly MetadataBuilder metadataBuilder;
-
+        private readonly TypeMapper mapper;
         private readonly Dictionary<string, TypeDeclaration> typeDefinitionMapping;
         private TypeDeclaration currentTypeDeclaration;
 
@@ -275,12 +275,14 @@ public WinRTTypeWriter(
             string assembly,
             string version,
             MetadataBuilder metadataBuilder,
-            Logger logger)
+            Logger logger,
+            TypeMapper mapper)
         {
             this.assembly = assembly;
             this.version = version;
             this.metadataBuilder = metadataBuilder;
             Logger = logger;
+            this.mapper = mapper;
             typeReferenceMapping = new Dictionary<string, TypeReferenceHandle>(StringComparer.Ordinal);
             assemblyReferenceMapping = new Dictionary<string, EntityHandle>(StringComparer.Ordinal);
             typeDefinitionMapping = new Dictionary<string, TypeDeclaration>(StringComparer.Ordinal);
@@ -435,9 +437,9 @@ private EntityHandle GetTypeReference(ISymbol symbol)
             var assembly = GetAssemblyForWinRTType(symbol);
             if (assembly == null)
             {
-                if (GeneratorHelper.MappedCSharpTypes.ContainsKey(fullType))
+                if (mapper.HasMappingForType(fullType))
                 {
-                    (@namespace, name, assembly, _, _) = GeneratorHelper.MappedCSharpTypes[fullType].GetMapping(currentTypeDeclaration.Node);
+                    (@namespace, name, assembly, _, _) = mapper.GetMappedType(fullType).GetMapping(currentTypeDeclaration.Node);
                     Logger.Log("custom mapping " + fullType + " to " + QualifiedName(@namespace, name) + " from " + assembly);
                 }
                 else
@@ -520,9 +522,9 @@ private void EncodeSymbol(Symbol symbol, SignatureTypeEncoder typeEncoder)
             else
             {
                 bool isValueType = symbol.Type.TypeKind == TypeKind.Enum || symbol.Type.TypeKind == TypeKind.Struct;
-                if (GeneratorHelper.MappedCSharpTypes.ContainsKey(QualifiedName(symbol.Type)))
+                if (mapper.HasMappingForType(QualifiedName(symbol.Type)))
                 {
-                    (_, _, _, _, isValueType) = GeneratorHelper.MappedCSharpTypes[QualifiedName(symbol.Type)].GetMapping(currentTypeDeclaration.Node);
+                    (_, _, _, _, isValueType) = mapper.GetMappedType(QualifiedName(symbol.Type)).GetMapping(currentTypeDeclaration.Node);
                 }
                 typeEncoder.Type(GetTypeReference(symbol.Type), isValueType);
             }
@@ -804,7 +806,7 @@ private void ProcessCustomMappedInterfaces(INamedTypeSymbol classSymbol)
             // Mark custom mapped interface members for removal later.
             // Note we want to also mark members from interfaces without mappings.
             foreach (var implementedInterface in GetInterfaces(classSymbol, true).
-                Where(symbol => GeneratorHelper.MappedCSharpTypes.ContainsKey(QualifiedName(symbol)) ||
+                Where(symbol => mapper.HasMappingForType(QualifiedName(symbol)) ||
                                 ImplementedInterfacesWithoutMapping.Contains(QualifiedName(symbol))))
             {
                 bool isPubliclyImplemented = false;
@@ -825,7 +827,7 @@ private void ProcessCustomMappedInterfaces(INamedTypeSymbol classSymbol)
             }
 
             foreach (var implementedInterface in GetInterfaces(classSymbol)
-                        .Where(symbol => GeneratorHelper.MappedCSharpTypes.ContainsKey(QualifiedName(symbol))))
+                        .Where(symbol => mapper.HasMappingForType(QualifiedName(symbol))))
             {
                 WriteCustomMappedTypeMembers(implementedInterface, true, isPublicImplementation[implementedInterface]);
             }
@@ -853,9 +855,9 @@ INamedTypeSymbol GetTypeByMetadataName(string metadataName)
         private string GetMappedQualifiedTypeName(ITypeSymbol symbol)
         {
             string qualifiedName = QualifiedName(symbol);
-            if (GeneratorHelper.MappedCSharpTypes.ContainsKey(qualifiedName))
+            if (mapper.HasMappingForType(qualifiedName))
             {
-                var (@namespace, mappedTypeName, _, _, _) = GeneratorHelper.MappedCSharpTypes[qualifiedName].GetMapping(currentTypeDeclaration.Node);
+                var (@namespace, mappedTypeName, _, _, _) = mapper.GetMappedType(qualifiedName).GetMapping(currentTypeDeclaration.Node);
                 qualifiedName = QualifiedName(@namespace, mappedTypeName);
                 if (symbol is INamedTypeSymbol namedType && namedType.TypeArguments.Length > 0)
                 {
@@ -874,7 +876,7 @@ private string GetMappedQualifiedTypeName(ITypeSymbol symbol)
 
         private void WriteCustomMappedTypeMembers(INamedTypeSymbol symbol, bool isDefinition, bool isPublic = true)
         {
-            var (_, mappedTypeName, _, _, _) = GeneratorHelper.MappedCSharpTypes[QualifiedName(symbol)].GetMapping(currentTypeDeclaration.Node);
+            var (_, mappedTypeName, _, _, _) = mapper.GetMappedType(QualifiedName(symbol)).GetMapping(currentTypeDeclaration.Node);
             string qualifiedName = GetMappedQualifiedTypeName(symbol);
 
             Logger.Log("writing custom mapped type members for " + mappedTypeName + " public: " + isPublic + " qualified name: " + qualifiedName);
@@ -1233,7 +1235,7 @@ void GatherPubliclyAccessibleInterfaces(ITypeSymbol symbol)
             GatherPubliclyAccessibleInterfaces(symbol);
 
             var baseType = symbol.BaseType;
-            while (baseType != null && !GeneratorHelper.IsWinRTType(baseType))
+            while (baseType != null && !GeneratorHelper.IsWinRTType(baseType, mapper))
             {
                 GatherPubliclyAccessibleInterfaces(baseType);
 
@@ -2440,9 +2442,9 @@ void AddType(INamedTypeSymbol type, bool treatAsProjectedType = false)
             {
                 AddProjectedType(type);
             }
-            else if (GeneratorHelper.MappedCSharpTypes.ContainsKey(qualifiedName))
+            else if (mapper.HasMappingForType(qualifiedName))
             {
-                var (@namespace, name, assembly, isSystemType, _) = GeneratorHelper.MappedCSharpTypes[qualifiedName].GetMapping();
+                var (@namespace, name, assembly, isSystemType, _) = mapper.GetMappedType(qualifiedName).GetMapping();
                 if (isSystemType)
                 {
                     var projectedType = Model.Compilation.GetTypeByMetadataName(QualifiedName(@namespace, name));
@@ -2534,7 +2536,7 @@ public void FinalizeGeneration()
 
                     Logger.Log("finalizing interface " + implementedInterfaceQualifiedNameWithGenerics);
                     var interfaceTypeDeclaration = typeDefinitionMapping[implementedInterfaceQualifiedNameWithGenerics];
-                    if (GeneratorHelper.MappedCSharpTypes.ContainsKey(QualifiedName(implementedInterface)))
+                    if (mapper.HasMappingForType(QualifiedName(implementedInterface)))
                     {
                         Logger.Log("adding MethodImpls for custom mapped interface");
                         foreach (var interfaceMember in interfaceTypeDeclaration.MethodReferences)
@@ -2665,11 +2667,11 @@ public void FinalizeGeneration()
 
         public void GenerateWinRTExposedClassAttributes(GeneratorExecutionContext context)
         {
-            bool IsWinRTType(ISymbol symbol)
+            bool IsWinRTType(ISymbol symbol, TypeMapper mapper)
             {
                 if (!SymbolEqualityComparer.Default.Equals(symbol.ContainingAssembly, context.Compilation.Assembly))
                 {
-                    return GeneratorHelper.IsWinRTType(symbol, IsWinRTType);
+                    return GeneratorHelper.IsWinRTType(symbol, (symbol, mapper) => IsWinRTType(symbol, mapper), mapper);
                 }
 
                 if (symbol is INamedTypeSymbol namedType)
@@ -2703,8 +2705,8 @@ typeDeclaration.Node is INamedTypeSymbol symbol &&
                     symbol.TypeKind == TypeKind.Class && 
                     !symbol.IsStatic)
                 {
-                    vtableAttributesToAdd.Add(WinRTAotSourceGenerator.GetVtableAttributeToAdd(symbol, IsWinRTType, context.Compilation, true, typeDeclaration.DefaultInterface));
-                    WinRTAotSourceGenerator.AddVtableAdapterTypeForKnownInterface(symbol, context.Compilation, IsWinRTType, vtableAttributesToAddOnLookupTable);
+                    vtableAttributesToAdd.Add(WinRTAotSourceGenerator.GetVtableAttributeToAdd(symbol, IsWinRTType, mapper, context.Compilation, true, typeDeclaration.DefaultInterface));
+                    WinRTAotSourceGenerator.AddVtableAdapterTypeForKnownInterface(symbol, context.Compilation, IsWinRTType, mapper, vtableAttributesToAddOnLookupTable);
                 }
             }
 
diff --git a/src/Directory.Build.props b/src/Directory.Build.props
index 009806607..b7d20d0ae 100644
--- a/src/Directory.Build.props
+++ b/src/Directory.Build.props
@@ -30,6 +30,8 @@
     <AppBuildTFMs Condition="'$(CIBuildReason)' == 'CI'">netcoreapp3.1;net6.0;net8.0</AppBuildTFMs>
     <LibBuildTFMs>netstandard2.0;net6.0;net8.0</LibBuildTFMs>
     <LibBuildTFMs Condition="'$(CIBuildReason)' == 'CI'">netstandard2.0;net6.0;net8.0</LibBuildTFMs>
+    <LibBuildTFMsNoNetStandard>net6.0;net8.0</LibBuildTFMsNoNetStandard>
+    <LibBuildTFMsNoNetStandard Condition="'$(CIBuildReason)' == 'CI'">net6.0;net8.0</LibBuildTFMsNoNetStandard>
     <TestsBuildTFMs>net6.0-windows10.0.19041.0;net7.0-windows10.0.19041.0</TestsBuildTFMs>
     <TestsBuildTFMs Condition="'$(CIBuildReason)' == 'CI'">net6.0-windows10.0.19041.0</TestsBuildTFMs>
     <FunctionalTestsBuildTFMs>net6.0;net8.0</FunctionalTestsBuildTFMs>
diff --git a/src/Perf/IIDOptimizer/GuidPatcher.cs b/src/Perf/IIDOptimizer/GuidPatcher.cs
index bd200dfd6..e12723150 100644
--- a/src/Perf/IIDOptimizer/GuidPatcher.cs
+++ b/src/Perf/IIDOptimizer/GuidPatcher.cs
@@ -72,12 +72,14 @@ public GuidPatcher(AssemblyDefinition winRTRuntime, AssemblyDefinition targetAss
             guidGeneratorType = null;
 
             TypeDefinition? typeExtensionsType = null;
+            TypeDefinition? wuxMuxProjectedInterfaceAttributeType = null;
 
             // Use the type definition if we are patching WinRT.Runtime, otherwise lookup the types as references 
             if (string.CompareOrdinal(assembly.Name.Name, "WinRT.Runtime") == 0)
             {
-                guidGeneratorType = winRTRuntimeAssembly.MainModule.Types.Where(typeDef => string.CompareOrdinal(typeDef.Name, "GuidGenerator") == 0).First();
-                typeExtensionsType = winRTRuntimeAssembly.MainModule.Types.Where(typeDef => string.CompareOrdinal(typeDef.Name, "TypeExtensions") == 0).First();
+                guidGeneratorType = winRTRuntimeAssembly.MainModule.Types.Where(typeDef => string.Equals(typeDef.Name, "GuidGenerator", StringComparison.Ordinal)).First();
+                typeExtensionsType = winRTRuntimeAssembly.MainModule.Types.Where(typeDef => string.Equals(typeDef.Name, "TypeExtensions", StringComparison.Ordinal)).First();
+                wuxMuxProjectedInterfaceAttributeType = winRTRuntimeAssembly.MainModule.Types.Where(typedef => string.Equals(typedef.Name, "WuxMuxProjectedInterfaceAttribute", StringComparison.Ordinal)).First();
             }
 
             foreach (var asm in assembly.MainModule.AssemblyReferences)
@@ -87,6 +89,7 @@ public GuidPatcher(AssemblyDefinition winRTRuntime, AssemblyDefinition targetAss
                     guidGeneratorType =
                         new TypeReference("WinRT", "GuidGenerator", assembly.MainModule, asm).Resolve();
                     typeExtensionsType = new TypeReference("WinRT", "TypeExtensions", assembly.MainModule, asm).Resolve();
+                    wuxMuxProjectedInterfaceAttributeType = new TypeReference("WinRT", "WuxMuxProjectedInterfaceAttribute", assembly.MainModule, asm).Resolve();
                 }
                 else if (string.CompareOrdinal(asm.Name, "System.Runtime.InteropServices") == 0)
                 {
@@ -101,7 +104,7 @@ public GuidPatcher(AssemblyDefinition winRTRuntime, AssemblyDefinition targetAss
                 getHelperTypeMethod = typeExtensionsType.Methods.First(m => String.CompareOrdinal(m.Name, "GetHelperType") == 0);
             }
 
-            signatureGenerator = new SignatureGenerator(assembly, guidAttributeType!, winRTRuntimeAssembly);
+            signatureGenerator = new SignatureGenerator(assembly, guidAttributeType!, wuxMuxProjectedInterfaceAttributeType!, winRTRuntimeAssembly);
             methodCache = new Dictionary<string, MethodReference>();
         }
 
diff --git a/src/Perf/IIDOptimizer/SignatureEmitter.cs b/src/Perf/IIDOptimizer/SignatureEmitter.cs
index aa3d6a393..3483105d8 100644
--- a/src/Perf/IIDOptimizer/SignatureEmitter.cs
+++ b/src/Perf/IIDOptimizer/SignatureEmitter.cs
@@ -35,6 +35,8 @@ sealed record RuntimeGenericSignatureStep(GenericParameter OriginalTypeParameter
 
         sealed record RuntimeCustomSignatureStep(MethodReference method) : SignatureStep;
 
+        sealed record FallbackSignatureStep(TypeReference type) : SignatureStep;
+
         public SignatureEmitter(TypeReference describedType, MethodDefinition guidDataGetterMethod)
         {
             this.describedType = describedType;
@@ -76,6 +78,16 @@ public void PushCustomSignature(MethodReference customSignatureMethod)
             signatureSteps.Add(new RuntimeCustomSignatureStep(customSignatureMethod));
         }
 
+        public void PushFallback(TypeReference type)
+        {
+            if (currentStringBuilder is not null)
+            {
+                signatureSteps.Add(new StringStep(currentStringBuilder.ToString()));
+                currentStringBuilder = null;
+            }
+            signatureSteps.Add(new FallbackSignatureStep(type));
+        }
+
         public void EmitGuidGetter(
             TypeDefinition guidDataBlockType,
             TypeDefinition implementationDetailsType,
@@ -289,6 +301,25 @@ private void GenerateGuidFactoryFromComplexSignature(TypeDefinition implementati
                             il.Emit(OpCodes.Stloc, fullSignatureLength);
                         }
                         break;
+                    case FallbackSignatureStep(TypeReference type):
+                        {
+                            // byte[] bytes = Encoding.UTF8.GetBytes(GetSignature(typeof(type)))
+                            il.Emit(OpCodes.Call, utf8EncodingGetter);
+                            il.Emit(OpCodes.Ldtoken, type);
+                            il.Emit(OpCodes.Call, getTypeFromHandleMethod);
+                            il.Emit(OpCodes.Call, getSignatureMethod);
+                            il.Emit(OpCodes.Callvirt, encodingGetBytes);
+                            il.Emit(OpCodes.Dup);
+                            // <locals[i]> = new ReadOnlySpan<byte>(bytes);
+                            il.Emit(OpCodes.Newobj, readOnlySpanOfByteArrayCtor);
+                            il.Emit(OpCodes.Stloc, signatureParts[i]);
+                            // signatureLength += bytes.Length
+                            il.Emit(OpCodes.Ldlen);
+                            il.Emit(OpCodes.Ldloc, fullSignatureLength);
+                            il.Emit(OpCodes.Add_Ovf);
+                            il.Emit(OpCodes.Stloc, fullSignatureLength);
+                        }
+                        break;
                     default:
                         il.Clear();
                         throw new InvalidOperationException();
diff --git a/src/Perf/IIDOptimizer/SignatureGenerator.cs b/src/Perf/IIDOptimizer/SignatureGenerator.cs
index 7c6fd6282..ce0e7e2ef 100644
--- a/src/Perf/IIDOptimizer/SignatureGenerator.cs
+++ b/src/Perf/IIDOptimizer/SignatureGenerator.cs
@@ -55,12 +55,14 @@ sealed class SignatureGenerator
     {
         private readonly AssemblyDefinition assembly;
         private readonly TypeDefinition guidAttributeType;
+        private readonly TypeDefinition wuxMuxProjectedInterfaceAttributeType;
         private readonly AssemblyDefinition winRTRuntimeAssembly;
 
-        public SignatureGenerator(AssemblyDefinition assembly, TypeDefinition guidAttributeType, AssemblyDefinition runtimeAssembly)
+        public SignatureGenerator(AssemblyDefinition assembly, TypeDefinition guidAttributeType, TypeDefinition wuxMuxProjectedInterfaceAttributeType, AssemblyDefinition runtimeAssembly)
         {
             this.assembly = assembly;
             this.guidAttributeType = guidAttributeType;
+            this.wuxMuxProjectedInterfaceAttributeType = wuxMuxProjectedInterfaceAttributeType;
             this.winRTRuntimeAssembly = runtimeAssembly;
         }
 
@@ -170,6 +172,25 @@ public SignaturePart GetSignatureParts(TypeReference type)
                 return new RuntimeClassSignature(type, GetSignatureParts(iface));
             }
 
+            // For types projected from WUX or MUX into .NET, we'll need to do a runtime lookup for the IID.
+            // TODO-WuxMux: We can instead take an option in the IID optimizer to hard-code the lookup for WUX or MUX when specified, which would be more efficient for scenarios where this is possible.
+            if (helperType?.Resolve().CustomAttributes.Any(attr => attr.AttributeType.Resolve() == wuxMuxProjectedInterfaceAttributeType) == true)
+            {
+                var getGuidSignatureMethod = new MethodReference("GetGuidSignature", assembly.MainModule.TypeSystem.String, helperType)
+                {
+                    HasThis = false
+                };
+
+                if (getGuidSignatureMethod.Resolve() is not null)
+                {
+                    return new CustomSignatureMethod(assembly.MainModule.ImportReference(getGuidSignatureMethod));
+                }
+                else
+                {
+                    throw new InvalidOperationException($"Unable to resolve GetGuidSignature method for type projected into .NET from WUX/MUX: {type.FullName}.");
+                }
+            }
+
             Guid? guidAttributeValue = type.ReadGuidFromAttribute(guidAttributeType, winRTRuntimeAssembly);
             if (guidAttributeValue == null)
             {
diff --git a/src/Projections/WinAppSDK/WinAppSDK.csproj b/src/Projections/WinAppSDK/WinAppSDK.csproj
index b77e179c6..5fd5ae330 100644
--- a/src/Projections/WinAppSDK/WinAppSDK.csproj
+++ b/src/Projections/WinAppSDK/WinAppSDK.csproj
@@ -35,6 +35,7 @@
       -include Windows.UI.Xaml.Media.Animation.ConditionallyIndependentlyAnimatableAttribute
       -include Windows.UI.Xaml.Media.Animation.IndependentlyAnimatableAttribute
       -include Windows.UI.Xaml.Media.Animation.ConditionallyIndependentlyAnimatableAttribute
+      -addition_exclude Windows.UI.Xaml.Media.Animation
     </CsWinRTFilters>
     <!--PkgMicrosoft_WindowsAppSDK is set in in obj\*.csproj.nuget.g.props with TargetFramework condition, doesn't support multi-targeting-->
     <PkgMicrosoft_WindowsAppSDK>$([MSBuild]::NormalizeDirectory('$(NuGetPackageRoot)', 'microsoft.windowsappsdk', '$(MicrosoftWinAppSDKVersion)'))</PkgMicrosoft_WindowsAppSDK>
diff --git a/src/Projections/WinUI/WinUI.csproj b/src/Projections/WinUI/WinUI.csproj
index a3b83d4f6..e5a1e4c35 100644
--- a/src/Projections/WinUI/WinUI.csproj
+++ b/src/Projections/WinUI/WinUI.csproj
@@ -37,7 +37,8 @@
 -include Windows.UI.Xaml.Markup.MarkupExtensionReturnTypeAttribute
 -include Windows.UI.Xaml.Media.Animation.ConditionallyIndependentlyAnimatableAttribute
 -include Windows.UI.Xaml.Media.Animation.IndependentlyAnimatableAttribute
--include Windows.UI.Xaml.Media.Animation.ConditionallyIndependentlyAnimatableAttribute      
+-include Windows.UI.Xaml.Media.Animation.ConditionallyIndependentlyAnimatableAttribute
+-addition_exclude Windows.UI.Xaml.Media.Animation
     </CsWinRTFilters>
     <!--PkgMicrosoft_WinUI is set in in obj\*.csproj.nuget.g.props with TargetFramework condition, doesn't support multi-targeting-->
     <PkgMicrosoft_WinUI Condition="'$(PkgMicrosoft_WinUI)'==''">$([MSBuild]::NormalizeDirectory('$(NuGetPackageRoot)', 'microsoft.winui', '$(MicrosoftWinUIVersion)'))</PkgMicrosoft_WinUI>
diff --git a/src/Projections/Windows.UI.Xaml/Module.cs b/src/Projections/Windows.UI.Xaml/Module.cs
new file mode 100644
index 000000000..636144eed
--- /dev/null
+++ b/src/Projections/Windows.UI.Xaml/Module.cs
@@ -0,0 +1,3 @@
+#if NET
+[assembly: global::System.Runtime.Versioning.SupportedOSPlatform("Windows")]
+#endif
diff --git a/src/Projections/Windows.UI.Xaml/Windows.UI.Xaml.csproj b/src/Projections/Windows.UI.Xaml/Windows.UI.Xaml.csproj
new file mode 100644
index 000000000..f4ca1fa5f
--- /dev/null
+++ b/src/Projections/Windows.UI.Xaml/Windows.UI.Xaml.csproj
@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>$(LibBuildTFMsNoNetStandard)</TargetFrameworks>
+    <Platforms>x64;x86</Platforms>
+    <AssemblyName>Microsoft.Windows.UI.Xaml</AssemblyName>
+    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.Numerics.Vectors" Version="4.5.0" />
+    <ProjectReference Include="..\..\WinRT.Runtime\WinRT.Runtime.csproj" />
+    <ProjectReference Include="..\..\cswinrt\cswinrt.vcxproj" />
+    <InternalsVisibleTo Include="UnitTest" />
+    <ProjectReference Include="..\..\Authoring\WinRT.SourceGenerator\WinRT.SourceGenerator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" SetPlatform="Platform=x64"/>
+    <ProjectReference Include="..\Windows\Windows.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <CsWinRTFilters>
+-exclude Windows
+-include Windows.UI.Xaml
+-exclude Windows.UI.Xaml.Media.Animation.ConditionallyIndependentlyAnimatableAttribute
+-addition_exclude Windows.UI.Xaml.Media.Animation
+    </CsWinRTFilters>
+  </PropertyGroup>
+ 
+</Project>
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.exe.manifest b/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.exe.manifest
new file mode 100644
index 000000000..3d69fa84a
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.exe.manifest
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity version="1.0.0.0" name="CppTestApp"/>
+  <file name="WinRT.Host.dll">
+    <activatableClass
+        name="AuthoringWuxTest.DisposableClass"
+        threadingModel="both"
+        xmlns="urn:schemas-microsoft-com:winrt.v1" />
+    <activatableClass
+        name="AuthoringWuxTest.CustomNotifyPropertyChanged"
+        threadingModel="both"
+        xmlns="urn:schemas-microsoft-com:winrt.v1" />
+    <activatableClass
+        name="AuthoringWuxTest.CustomNotifyCollectionChanged"
+        threadingModel="both"
+        xmlns="urn:schemas-microsoft-com:winrt.v1" />
+    <activatableClass
+        name="AuthoringWuxTest.MultipleInterfaceMappingClass"
+        threadingModel="both"
+        xmlns="urn:schemas-microsoft-com:winrt.v1" />
+  </file>
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+	  <maxversiontested Id="10.0.18226.0"/>
+	</application>
+  </compatibility>
+</assembly>
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.vcxproj b/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.vcxproj
new file mode 100644
index 000000000..64c641b2f
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.vcxproj
@@ -0,0 +1,212 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.props" Condition="Exists('..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.props')" />
+  <Import Project="..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.props" Condition="Exists('..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.props')" />
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|ARM64">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM64">
+      <Configuration>Release</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{A04A0416-5E35-4DD0-8226-63D941B28467}</ProjectGuid>
+    <Keyword>Win32Proj</Keyword>
+    <RootNamespace>AuthoringConsumptionTest</RootNamespace>
+    <ConfigurationType>Application</ConfigurationType>
+    <PlatformToolset>v143</PlatformToolset>
+    <PlatformToolset Condition="'$(VisualStudioVersion)' == '16.0'">v142</PlatformToolset>
+    <CharacterSet>Unicode</CharacterSet>
+    <_WinMDPlatform>$(Platform)</_WinMDPlatform>
+    <_WinMDPlatform Condition="'$(Platform)' == 'Win32'">x86</_WinMDPlatform>
+    <EnablePriGenTooling>false</EnablePriGenTooling>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings" />
+  <ImportGroup Label="Shared" />
+  <ImportGroup Label="PropertySheets" />
+  <PropertyGroup Label="UserMacros" />
+  <ItemGroup>
+    <ClInclude Include="pch.h" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="test.cpp" />
+    <ClCompile Include="pch.cpp">
+      <PrecompiledHeader>Create</PrecompiledHeader>
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="Directory.Build.targets" />
+    <None Include="DoNotImport_MsAppxPackageTargets.targets" />
+    <None Include="packages.config" />
+    <None Include="WinRT.Host.runtimeconfig.json">
+      <DeploymentContent Condition="'$(Configuration)|$(Platform)'=='Release|x64'">true</DeploymentContent>
+      <DeploymentContent Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">true</DeploymentContent>
+      <DeploymentContent Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">true</DeploymentContent>
+      <DeploymentContent Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">true</DeploymentContent>
+    </None>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\Projections\Windows\Windows.csproj">
+      <Project>{ffa9a78b-f53f-43ee-af87-24a80f4c330a}</Project>
+      <SetTargetFramework>TargetFramework=net6.0</SetTargetFramework>
+    </ProjectReference>
+    <ProjectReference Include="..\..\Authoring\WinRT.Host.Shim\WinRT.Host.Shim.csproj">
+      <Project>{0bb8f82d-874e-45aa-bca3-20ce0562164a}</Project>
+      <SetTargetFramework>TargetFramework=net6.0</SetTargetFramework>
+    </ProjectReference>
+    <ProjectReference Include="..\..\Authoring\WinRT.Host\WinRT.Host.vcxproj">
+      <Project>{7e33bcb7-19c5-4061-981d-ba695322708a}</Project>
+    </ProjectReference>
+    <ProjectReference Include="..\..\WinRT.Runtime\WinRT.Runtime.csproj">
+      <Project>{25244ced-966e-45f2-9711-1f51e951ff89}</Project>
+      <SetTargetFramework>TargetFramework=net6.0</SetTargetFramework>
+    </ProjectReference>
+    <ProjectReference Include="..\AuthoringWuxTest\AuthoringWuxTest.csproj">
+      <Project>{d60cfcad-4a13-4047-91c8-9d7df4753493}</Project>
+      <SetTargetFramework>TargetFramework=net6.0</SetTargetFramework>
+    </ProjectReference>
+  </ItemGroup>
+  <ItemGroup>
+    <Reference Include="AuthoringWuxTest">
+      <HintPath>..\AuthoringWuxTest\bin\$(_WinMDPlatform)\$(Configuration)\net6.0\AuthoringWuxTest.winmd</HintPath>
+      <IsWinMDFile>true</IsWinMDFile>
+    </Reference>
+  </ItemGroup>
+  <ItemGroup>
+    <Manifest Include="AuthoringWuxConsumptionTest.exe.manifest" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+    <Import Project="..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.targets" Condition="Exists('..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.targets')" />
+    <Import Project="..\..\packages\Microsoft.VCRTForwarders.140.1.0.7\build\native\Microsoft.VCRTForwarders.140.targets" Condition="Exists('..\..\packages\Microsoft.VCRTForwarders.140.1.0.7\build\native\Microsoft.VCRTForwarders.140.targets')" />
+    <Import Project="..\..\packages\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.1.8.1.6\build\native\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.targets" Condition="Exists('..\..\packages\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.1.8.1.6\build\native\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.targets')" />
+    <Import Project="..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.targets" Condition="Exists('..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.targets')" />
+  </ImportGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <ClCompile>
+      <PrecompiledHeader>Use</PrecompiledHeader>
+      <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
+      <Optimization>Disabled</Optimization>
+      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
+      <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
+      <WarningLevel>Level3</WarningLevel>
+    </ClCompile>
+    <Link>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <ClCompile>
+      <PrecompiledHeader>Use</PrecompiledHeader>
+      <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
+      <Optimization>Disabled</Optimization>
+      <PreprocessorDefinitions>X64;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
+      <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
+      <WarningLevel>Level3</WarningLevel>
+    </ClCompile>
+    <Link>
+      <GenerateDebugInformation>DebugFull</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">
+    <ClCompile>
+      <PrecompiledHeader>Use</PrecompiledHeader>
+      <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
+      <Optimization>Disabled</Optimization>
+      <PreprocessorDefinitions>X64;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
+      <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
+      <WarningLevel>Level3</WarningLevel>
+    </ClCompile>
+    <Link>
+      <GenerateDebugInformation>DebugFull</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <ClCompile>
+      <PrecompiledHeader>Use</PrecompiledHeader>
+      <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
+      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
+      <WarningLevel>Level3</WarningLevel>
+      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
+    </ClCompile>
+    <Link>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+      <OptimizeReferences>true</OptimizeReferences>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <ClCompile>
+      <PrecompiledHeader>Use</PrecompiledHeader>
+      <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
+      <PreprocessorDefinitions>X64;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
+      <WarningLevel>Level3</WarningLevel>
+      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
+    </ClCompile>
+    <Link>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+      <OptimizeReferences>true</OptimizeReferences>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">
+    <ClCompile>
+      <PrecompiledHeader>Use</PrecompiledHeader>
+      <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
+      <PreprocessorDefinitions>X64;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
+      <WarningLevel>Level3</WarningLevel>
+      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
+    </ClCompile>
+    <Link>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+      <OptimizeReferences>true</OptimizeReferences>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+    </Link>
+  </ItemDefinitionGroup>
+  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
+    <PropertyGroup>
+      <ErrorText>This project references NuGet package(s) that are missing on this computer. Use NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
+    </PropertyGroup>
+    <Error Condition="!Exists('..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.props')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.props'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.Windows.CppWinRT.2.0.201113.7\build\native\Microsoft.Windows.CppWinRT.targets'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.VCRTForwarders.140.1.0.7\build\native\Microsoft.VCRTForwarders.140.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.VCRTForwarders.140.1.0.7\build\native\Microsoft.VCRTForwarders.140.targets'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.1.8.1.6\build\native\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.1.8.1.6\build\native\Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn.targets'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.props')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.props'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.Windows.SDK.BuildTools.10.0.22000.194\build\Microsoft.Windows.SDK.BuildTools.targets'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.WindowsAppSDK.1.1.5\build\native\Microsoft.WindowsAppSDK.props')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.WindowsAppSDK.1.1.5\build\native\Microsoft.WindowsAppSDK.props'))" />
+    <Error Condition="!Exists('..\..\packages\Microsoft.WindowsAppSDK.1.1.5\build\native\Microsoft.WindowsAppSDK.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\Microsoft.WindowsAppSDK.1.1.5\build\native\Microsoft.WindowsAppSDK.targets'))" />
+  </Target>
+</Project>
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.vcxproj.filters b/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.vcxproj.filters
new file mode 100644
index 000000000..1332cff35
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/AuthoringWuxConsumptionTest.vcxproj.filters
@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <Filter Include="Source Files">
+      <UniqueIdentifier>{4FC737F1-C7A5-4376-A066-2A32D752A2FF}</UniqueIdentifier>
+      <Extensions>cpp;c;cc;cxx;def;odl;idl;hpj;bat;asm;asmx</Extensions>
+    </Filter>
+    <Filter Include="Header Files">
+      <UniqueIdentifier>{93995380-89BD-4b04-88EB-625FBE52EBFB}</UniqueIdentifier>
+      <Extensions>h;hh;hpp;hxx;hm;inl;inc;xsd</Extensions>
+    </Filter>
+    <Filter Include="Resource Files">
+      <UniqueIdentifier>{67DA6AB6-F800-4c08-8B7A-83BB121AAD01}</UniqueIdentifier>
+      <Extensions>rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms</Extensions>
+    </Filter>
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="pch.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="pch.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="test.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="packages.config" />
+    <None Include="Directory.Build.targets" />
+    <None Include="WinRT.Host.runtimeconfig.json" />
+    <None Include="DoNotImport_MsAppxPackageTargets.targets" />
+  </ItemGroup>
+  <ItemGroup>
+    <Manifest Include="AuthoringWuxConsumptionTest.exe.manifest" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxConsumptionTest/Directory.Build.targets b/src/Tests/AuthoringWuxConsumptionTest/Directory.Build.targets
new file mode 100644
index 000000000..623267b30
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/Directory.Build.targets
@@ -0,0 +1,16 @@
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+
+  <PropertyGroup>
+    <MsAppxPackageTargets>$(MSBuildProjectDirectory)/DoNotImport_MsAppxPackageTargets.targets</MsAppxPackageTargets>
+    <PrepareForRunDependsOn>CopyTestAssets;$(PrepareForRunDependsOn)</PrepareForRunDependsOn>
+  </PropertyGroup>
+
+  <Target Name="CopyTestAssets">
+    <Copy SourceFiles="$(BuildOutDir)WinRT.Host\bin\WinRT.Host.dll"
+          DestinationFiles="$(OutDir)WinRT.Host.dll" 
+          UseHardlinksIfPossible="false" SkipUnchangedFiles="true" />
+  </Target>  
+  
+  <Import Project="$([MSBuild]::GetPathOfFileAbove('Directory.Build.targets', '$(MSBuildThisFileDirectory)../'))" />
+
+</Project>
diff --git a/src/Tests/AuthoringWuxConsumptionTest/DoNotImport_MsAppxPackageTargets.targets b/src/Tests/AuthoringWuxConsumptionTest/DoNotImport_MsAppxPackageTargets.targets
new file mode 100644
index 000000000..bcb335b80
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/DoNotImport_MsAppxPackageTargets.targets
@@ -0,0 +1,5 @@
+<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+
+  <!-- Workaround: not every project that references the WinUI nuget wants to build a PRI file -->
+
+</Project>
diff --git a/src/Tests/AuthoringWuxConsumptionTest/WinRT.Host.runtimeconfig.json b/src/Tests/AuthoringWuxConsumptionTest/WinRT.Host.runtimeconfig.json
new file mode 100644
index 000000000..c625b0c81
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/WinRT.Host.runtimeconfig.json
@@ -0,0 +1,13 @@
+{
+  "runtimeOptions": {
+    "tfm": "net6.0",
+    "rollForward": "LatestMinor",
+    "framework": {
+      "name": "Microsoft.NETCore.App",
+      "version": "6.0.0"
+    },
+    "configProperties": {
+      "CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS": "true"
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxConsumptionTest/packages.config b/src/Tests/AuthoringWuxConsumptionTest/packages.config
new file mode 100644
index 000000000..98b40a750
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/packages.config
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Microsoft.googletest.v140.windesktop.msvcstl.static.rt-dyn" version="1.8.1.6" targetFramework="native" />
+  <package id="Microsoft.VCRTForwarders.140" version="1.0.7" targetFramework="native" />
+  <package id="Microsoft.Windows.CppWinRT" version="2.0.201113.7" targetFramework="native" />
+  <package id="Microsoft.Windows.SDK.BuildTools" version="10.0.22000.194" targetFramework="native" />
+</packages>
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxConsumptionTest/pch.cpp b/src/Tests/AuthoringWuxConsumptionTest/pch.cpp
new file mode 100644
index 000000000..bcb5590be
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/pch.cpp
@@ -0,0 +1 @@
+#include "pch.h"
diff --git a/src/Tests/AuthoringWuxConsumptionTest/pch.h b/src/Tests/AuthoringWuxConsumptionTest/pch.h
new file mode 100644
index 000000000..db3c5d270
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/pch.h
@@ -0,0 +1,26 @@
+#pragma once
+
+// Undefine GetCurrentTime macro to prevent
+// conflict with Storyboard::GetCurrentTime
+#undef GetCurrentTime
+
+#include <Windows.h>
+#include <winrt/Windows.Foundation.h>
+#include <winrt/Windows.Foundation.Collections.h>
+
+#pragma push_macro("X86")
+#pragma push_macro("X64")
+#undef X86
+#undef X64
+#include "winrt/Windows.System.h"
+#pragma pop_macro("X64")
+#pragma pop_macro("X86")
+
+#include <winrt/Windows.UI.Xaml.h>
+#include <winrt/Windows.UI.Xaml.Interop.h>
+#include <winrt/Windows.UI.Xaml.Data.h>
+#include <winrt/Windows.UI.Xaml.Hosting.h>
+
+#include <winrt/AuthoringWuxTest.h>
+
+#include "gtest/gtest.h"
diff --git a/src/Tests/AuthoringWuxConsumptionTest/test.cpp b/src/Tests/AuthoringWuxConsumptionTest/test.cpp
new file mode 100644
index 000000000..b182b935c
--- /dev/null
+++ b/src/Tests/AuthoringWuxConsumptionTest/test.cpp
@@ -0,0 +1,75 @@
+#include "pch.h"
+
+using namespace winrt;
+using namespace Windows::Foundation;
+using namespace AuthoringWuxTest;
+
+TEST(AuthoringWuxTest, Collections)
+{
+    DisposableClass disposed;
+    disposed.Close();
+    MultipleInterfaceMappingClass multipleInterfaces;
+    Windows::UI::Xaml::Interop::IBindableIterable bindable = multipleInterfaces;
+    Windows::Foundation::Collections::IVector<DisposableClass> vector = multipleInterfaces;
+    Windows::UI::Xaml::Interop::IBindableVector bindableVector = multipleInterfaces;
+    EXPECT_EQ(vector.Size(), 0);
+    EXPECT_EQ(bindableVector.Size(), 0);
+    vector.Append(DisposableClass());
+    vector.Append(DisposableClass());
+    vector.Append(disposed);
+    bindableVector.Append(DisposableClass());
+    EXPECT_EQ(vector.Size(), 4);
+    EXPECT_EQ(bindableVector.Size(), 4);
+
+    auto first = vector.First();
+    EXPECT_TRUE(first.HasCurrent());
+    EXPECT_FALSE(first.Current().IsDisposed());
+    auto bindableFirst = bindable.First();
+    EXPECT_TRUE(bindableFirst.HasCurrent());
+    EXPECT_FALSE(bindableFirst.Current().as<DisposableClass>().IsDisposed());
+    bindableFirst.Current().as<DisposableClass>().Close();
+    EXPECT_TRUE(first.Current().IsDisposed());
+    EXPECT_FALSE(vector.GetAt(1).IsDisposed());
+    EXPECT_TRUE(vector.GetAt(2).IsDisposed());
+    EXPECT_TRUE(bindableVector.First().Current().as<DisposableClass>().IsDisposed());
+    EXPECT_FALSE(bindableVector.GetAt(3).as<DisposableClass>().IsDisposed());
+    EXPECT_TRUE(bindableVector.GetAt(2).as<DisposableClass>().IsDisposed());
+    for (auto obj : vector.GetView())
+    {
+        obj.Close();
+    }
+
+    std::array<DisposableClass, 2> view{};
+    EXPECT_EQ(vector.GetMany(1, view), 2);
+    EXPECT_EQ(view.size(), 2);
+    for (auto& obj : view)
+    {
+        EXPECT_TRUE(obj.IsDisposed());
+    }
+}
+
+TEST(AuthoringWuxTest, PropertyChanged)
+{
+    CustomNotifyPropertyChanged customNotifyPropertyChanged;
+    Windows::UI::Xaml::Data::INotifyPropertyChanged propChanged = customNotifyPropertyChanged;
+    winrt::hstring propName = L"Number";
+    bool eventTriggered = false;
+    auto token = propChanged.PropertyChanged(auto_revoke, [&eventTriggered, &propName](IInspectable sender, Windows::UI::Xaml::Data::PropertyChangedEventArgs args)
+    {
+        eventTriggered = (args.PropertyName() == propName);
+    });
+
+    customNotifyPropertyChanged.RaisePropertyChanged(propName);
+
+    EXPECT_TRUE(eventTriggered);
+}
+
+int main(int argc, char** argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    winrt::init_apartment(winrt::apartment_type::single_threaded);
+    auto manager = winrt::Windows::UI::Xaml::Hosting::WindowsXamlManager::InitializeForCurrentThread();
+    int result = RUN_ALL_TESTS();
+    manager.Close();
+    return result;
+}
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxTest/AuthoringWuxTest.csproj b/src/Tests/AuthoringWuxTest/AuthoringWuxTest.csproj
new file mode 100644
index 000000000..fbd8d334e
--- /dev/null
+++ b/src/Tests/AuthoringWuxTest/AuthoringWuxTest.csproj
@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Platforms>x64;x86</Platforms>
+    <CsWinRTComponent>true</CsWinRTComponent>
+    <IsTrimmable>true</IsTrimmable>
+    <CsWinRTUIXamlProjections>WindowsUIXaml</CsWinRTUIXamlProjections>
+    <!-- CsWinRTEnableLogging helps to diagnose generation issues -->
+    <!-- <CsWinRTEnableLogging>true</CsWinRTEnableLogging> -->
+    <!--<CsWinRTKeepGeneratedSources>true</CsWinRTKeepGeneratedSources>--> 
+  </PropertyGroup>
+  
+  <ItemGroup>    
+    <ProjectReference Include="..\..\Projections\Windows\Windows.csproj" />    
+    <ProjectReference Include="..\..\Projections\Windows.UI.Xaml\Windows.UI.Xaml.csproj" />
+    <ProjectReference Include="..\..\Authoring\WinRT.SourceGenerator\WinRT.SourceGenerator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
+    <ProjectReference Include="..\..\cswinrt\cswinrt.vcxproj" />
+    <ProjectReference Include="..\..\WinRT.Runtime\WinRT.Runtime.csproj" />
+  </ItemGroup>
+
+</Project>
\ No newline at end of file
diff --git a/src/Tests/AuthoringWuxTest/Directory.Build.props b/src/Tests/AuthoringWuxTest/Directory.Build.props
new file mode 100644
index 000000000..4cf186e3d
--- /dev/null
+++ b/src/Tests/AuthoringWuxTest/Directory.Build.props
@@ -0,0 +1,9 @@
+<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" >
+
+  <PropertyGroup>
+    <SimulateCsWinRTNugetReference>true</SimulateCsWinRTNugetReference>
+  </PropertyGroup>
+  
+  <Import Project="$([MSBuild]::GetPathOfFileAbove('Directory.Build.props', '$(MSBuildThisFileDirectory)../'))" />
+
+</Project>
diff --git a/src/Tests/AuthoringWuxTest/Directory.Build.targets b/src/Tests/AuthoringWuxTest/Directory.Build.targets
new file mode 100644
index 000000000..8dde12d1b
--- /dev/null
+++ b/src/Tests/AuthoringWuxTest/Directory.Build.targets
@@ -0,0 +1,5 @@
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+
+  <Import Project="$([MSBuild]::GetPathOfFileAbove('Directory.Build.targets', '$(MSBuildThisFileDirectory)../'))" />
+
+</Project>
diff --git a/src/Tests/AuthoringWuxTest/Module.cs b/src/Tests/AuthoringWuxTest/Module.cs
new file mode 100644
index 000000000..636144eed
--- /dev/null
+++ b/src/Tests/AuthoringWuxTest/Module.cs
@@ -0,0 +1,3 @@
+#if NET
+[assembly: global::System.Runtime.Versioning.SupportedOSPlatform("Windows")]
+#endif
diff --git a/src/Tests/AuthoringWuxTest/Program.cs b/src/Tests/AuthoringWuxTest/Program.cs
new file mode 100644
index 000000000..004a3cb23
--- /dev/null
+++ b/src/Tests/AuthoringWuxTest/Program.cs
@@ -0,0 +1,171 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.ComponentModel;
+
+#pragma warning disable CA1416
+
+namespace AuthoringWuxTest
+{
+    public sealed class DisposableClass : IDisposable
+    {
+        public bool IsDisposed { get; set; }
+
+        public DisposableClass()
+        {
+            IsDisposed = false;
+        }
+
+        public void Dispose()
+        {
+            IsDisposed = true;
+        }
+    }
+    public sealed class CustomNotifyPropertyChanged : INotifyPropertyChanged
+    {
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        public void RaisePropertyChanged(string propertyName)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+
+    public sealed class CustomNotifyCollectionChanged : INotifyCollectionChanged
+    {
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
+
+        public void RaiseCollectionChanged(NotifyCollectionChangedEventArgs args)
+        {
+            CollectionChanged?.Invoke(this, args);
+        }
+    }
+
+    public sealed class CustomEnumerable : IEnumerable
+    {
+        private IEnumerable _enumerable;
+
+        public CustomEnumerable(IEnumerable enumerable)
+        {
+            _enumerable = enumerable;
+        }
+
+        public IEnumerator GetEnumerator()
+        {
+            return _enumerable.GetEnumerator();
+        }
+    }
+
+    public sealed class MultipleInterfaceMappingClass : IList<DisposableClass>, IList
+    {
+        private List<DisposableClass> _list = new List<DisposableClass>();
+
+        DisposableClass IList<DisposableClass>.this[int index] { get => _list[index]; set => _list[index] = value; }
+        object IList.this[int index] { get => _list[index]; set => ((IList)_list) [index] = value; }
+
+        int ICollection<DisposableClass>.Count => _list.Count;
+
+        int ICollection.Count => _list.Count;
+
+        bool ICollection<DisposableClass>.IsReadOnly => true;
+
+        bool IList.IsReadOnly => true;
+
+        bool IList.IsFixedSize => false;
+
+        bool ICollection.IsSynchronized => true;
+
+        object ICollection.SyncRoot => ((ICollection) _list).SyncRoot;
+
+        void ICollection<DisposableClass>.Add(DisposableClass item)
+        {
+            _list.Add(item);
+        }
+
+        int IList.Add(object value)
+        {
+            return ((IList) _list).Add(value);
+        }
+
+        void ICollection<DisposableClass>.Clear()
+        {
+            _list.Clear();
+        }
+
+        void IList.Clear()
+        {
+            _list.Clear();
+        }
+
+        bool ICollection<DisposableClass>.Contains(DisposableClass item)
+        {
+            return _list.Contains(item);
+        }
+
+        bool IList.Contains(object value)
+        {
+            return ((IList) _list).Contains(value);
+        }
+
+        void ICollection<DisposableClass>.CopyTo(DisposableClass[] array, int arrayIndex)
+        {
+            _list.CopyTo(array, arrayIndex);
+        }
+
+        void ICollection.CopyTo(Array array, int index)
+        {
+             ((ICollection) _list).CopyTo(array, index);
+        }
+
+        IEnumerator<DisposableClass> IEnumerable<DisposableClass>.GetEnumerator()
+        {
+            return _list.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return _list.GetEnumerator();
+        }
+
+        int IList<DisposableClass>.IndexOf(DisposableClass item)
+        {
+            return _list.IndexOf(item);
+        }
+
+        int IList.IndexOf(object value)
+        {
+            return ((IList) _list).IndexOf(value);
+        }
+
+        void IList<DisposableClass>.Insert(int index, DisposableClass item)
+        {
+            _list.Insert(index, item);
+        }
+
+        void IList.Insert(int index, object value)
+        {
+            ((IList) _list).Insert(index, value);
+        }
+
+        bool ICollection<DisposableClass>.Remove(DisposableClass item)
+        {
+            return _list.Remove(item);
+        }
+
+        void IList.Remove(object value)
+        {
+            ((IList) _list).Remove(value);
+        }
+
+        void IList<DisposableClass>.RemoveAt(int index)
+        {
+            _list.RemoveAt(index);
+        }
+
+        void IList.RemoveAt(int index)
+        {
+            _list.RemoveAt(index);
+        }
+    }
+}
diff --git a/src/Tests/AuthoringWuxTest/Properties/launchSettings.json b/src/Tests/AuthoringWuxTest/Properties/launchSettings.json
new file mode 100644
index 000000000..c05aeebf5
--- /dev/null
+++ b/src/Tests/AuthoringWuxTest/Properties/launchSettings.json
@@ -0,0 +1,8 @@
+{
+  "profiles": {
+    "AuthoringSample": {
+      "commandName": "Project",
+      "nativeDebugging": true
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/WinRT.Runtime/Configuration/FeatureSwitches.cs b/src/WinRT.Runtime/Configuration/FeatureSwitches.cs
index dbba4db98..41b785de5 100644
--- a/src/WinRT.Runtime/Configuration/FeatureSwitches.cs
+++ b/src/WinRT.Runtime/Configuration/FeatureSwitches.cs
@@ -4,8 +4,8 @@
 using System;
 using System.Runtime.CompilerServices;
 
-namespace WinRT
-{
+namespace WinRT
+{
     /// <summary>
     /// A container for all shared <see cref="AppContext"/> configuration switches for CsWinRT.
     /// </summary>
@@ -19,158 +19,177 @@ namespace WinRT
     /// For more info, see <see href="https://github.com/dotnet/runtime/blob/main/docs/workflow/trimming/feature-switches.md#adding-new-feature-switch"/>.
     /// </para>
     /// </remarks>
-    internal static class FeatureSwitches
-    {
+    internal static class FeatureSwitches
+    {
         /// <summary>
         /// The configuration property name for <see cref="EnableDynamicObjectsSupport"/>.
         /// </summary>
-        private const string EnablesDynamicObjectsSupportPropertyName = "CSWINRT_ENABLE_DYNAMIC_OBJECTS_SUPPORT";
-
+        private const string EnableDynamicObjectsSupportPropertyName = "CSWINRT_ENABLE_DYNAMIC_OBJECTS_SUPPORT";
+
         /// <summary>
         /// The configuration property name for <see cref="UseExceptionResourceKeys"/>.
         /// </summary>
-        private const string UseExceptionResourceKeysPropertyName = "CSWINRT_USE_EXCEPTION_RESOURCE_KEYS";
-
+        private const string UseExceptionResourceKeysPropertyName = "CSWINRT_USE_EXCEPTION_RESOURCE_KEYS";
+
         /// <summary>
         /// The configuration property name for <see cref="EnableDefaultCustomTypeMappings"/>.
         /// </summary>
-        private const string EnableDefaultCustomTypeMappingsPropertyName = "CSWINRT_ENABLE_DEFAULT_CUSTOM_TYPE_MAPPINGS";
-
+        private const string EnableDefaultCustomTypeMappingsPropertyName = "CSWINRT_ENABLE_DEFAULT_CUSTOM_TYPE_MAPPINGS";
+
         /// <summary>
         /// The configuration property name for <see cref="EnableICustomPropertyProviderSupport"/>.
         /// </summary>
-        private const string EnableICustomPropertyProviderSupportPropertyName = "CSWINRT_ENABLE_ICUSTOMPROPERTYPROVIDER_SUPPORT";
-
+        private const string EnableICustomPropertyProviderSupportPropertyName = "CSWINRT_ENABLE_ICUSTOMPROPERTYPROVIDER_SUPPORT";
+
         /// <summary>
         /// The configuration property name for <see cref="EnableIReferenceSupport"/>.
         /// </summary>
-        private const string EnableIReferenceSupportPropertyName = "CSWINRT_ENABLE_IREFERENCE_SUPPORT";
-
+        private const string EnableIReferenceSupportPropertyName = "CSWINRT_ENABLE_IREFERENCE_SUPPORT";
+
         /// <summary>
         /// The configuration property name for <see cref="EnableIDynamicInterfaceCastableSupport"/>.
         /// </summary>
-        private const string EnableIDynamicInterfaceCastableSupportPropertyName = "CSWINRT_ENABLE_IDYNAMICINTERFACECASTABLE";
-
+        private const string EnableIDynamicInterfaceCastableSupportPropertyName = "CSWINRT_ENABLE_IDYNAMICINTERFACECASTABLE";
+
+        /// <summary>
+        /// The configuration property name for <see cref="UseWindowsUIXamlProjections"/>.
+        /// </summary>
+        private const string UseWindowsUIXamlProjectionsPropertyName = "CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS";
+
         /// <summary>
         /// The backing field for <see cref="EnableDynamicObjectsSupport"/>.
         /// </summary>
-        private static int _enableDynamicObjectsSupportEnabled;
-
+        private static int _enableDynamicObjectsSupport;
+
         /// <summary>
         /// The backing field for <see cref="UseExceptionResourceKeys"/>.
         /// </summary>
-        private static int _useExceptionResourceKeys;
-
+        private static int _useExceptionResourceKeys;
+
         /// <summary>
         /// The backing field for <see cref="EnableDefaultCustomTypeMappings"/>.
         /// </summary>
-        private static int _enableDefaultCustomTypeMappings;
-
+        private static int _enableDefaultCustomTypeMappings;
+
         /// <summary>
         /// The backing field for <see cref="EnableICustomPropertyProviderSupport"/>.
         /// </summary>
-        private static int _enableICustomPropertyProviderSupport;
-
+        private static int _enableICustomPropertyProviderSupport;
+
         /// <summary>
         /// The backing field for <see cref="EnableIReferenceSupport"/>.
         /// </summary>
-        private static int _enableIReferenceSupport;
-
+        private static int _enableIReferenceSupport;
+
         /// <summary>
         /// The backing field for <see cref="EnableIDynamicInterfaceCastableSupport"/>.
         /// </summary>
-        private static int _enableIDynamicInterfaceCastableSupport;
-
+        private static int _enableIDynamicInterfaceCastableSupport;
+
+        /// <summary>
+        /// The backing field for <see cref="UseWindowsUIXamlProjections"/>.
+        /// </summary>
+        private static int _useWindowsUIXamlProjections;
+
         /// <summary>
         /// Gets a value indicating whether or not projections support for dynamic objects is enabled (defaults to <see langword="true"/>).
         /// </summary>
-        public static bool EnableDynamicObjectsSupport
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get => GetConfigurationValue(EnablesDynamicObjectsSupportPropertyName, ref _enableDynamicObjectsSupportEnabled, true);
-        }
-
+        public static bool EnableDynamicObjectsSupport
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(EnableDynamicObjectsSupportPropertyName, ref _enableDynamicObjectsSupport, true);
+        }
+
         /// <summary>
         /// Gets a value indicating whether or not exceptions should use resource keys rather than localized messages (defaults to <see langword="false"/>).
         /// </summary>
-        public static bool UseExceptionResourceKeys
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get => GetConfigurationValue(UseExceptionResourceKeysPropertyName, ref _useExceptionResourceKeys, false);
-        }
-
+        public static bool UseExceptionResourceKeys
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(UseExceptionResourceKeysPropertyName, ref _useExceptionResourceKeys, false);
+        }
+
         /// <summary>
         /// Gets a value indicating whether or not <see cref="Projections"/> should initialize all default type mappings automatically (defaults to <see langword="true"/>).
         /// </summary>
-        public static bool EnableDefaultCustomTypeMappings
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get => GetConfigurationValue(EnableDefaultCustomTypeMappingsPropertyName, ref _enableDefaultCustomTypeMappings, true);
-        }
-
+        public static bool EnableDefaultCustomTypeMappings
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(EnableDefaultCustomTypeMappingsPropertyName, ref _enableDefaultCustomTypeMappings, true);
+        }
+
         /// <summary>
         /// Gets a value indicating whether or not <see cref="ABI.Microsoft.UI.Xaml.Data.ManagedCustomPropertyProviderVftbl"/> should be enabled (defaults to <see langword="true"/>).
         /// </summary>
-        public static bool EnableICustomPropertyProviderSupport
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get => GetConfigurationValue(EnableICustomPropertyProviderSupportPropertyName, ref _enableICustomPropertyProviderSupport, true);
-        }
-
+        public static bool EnableICustomPropertyProviderSupport
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(EnableICustomPropertyProviderSupportPropertyName, ref _enableICustomPropertyProviderSupport, true);
+        }
+
         /// <summary>
         /// Gets a value indicating whether or not <c>IReference&lt;T&gt;</c>, <c>IReferenceArray&lt;T&gt;</c> and <c>IPropertyValue</c> CCW implementations should be supported (defaults to <see langword="true"/>).
         /// </summary>
-        public static bool EnableIReferenceSupport
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get => GetConfigurationValue(EnableIReferenceSupportPropertyName, ref _enableIReferenceSupport, true);
-        }
-
+        public static bool EnableIReferenceSupport
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(EnableIReferenceSupportPropertyName, ref _enableIReferenceSupport, true);
+        }
+
         /// <summary>
         /// Gets a value indicating whether or not <see cref="System.Runtime.InteropServices.IDynamicInterfaceCastable"/> should be supported by RCW types (defaults to <see langword="true"/>).
         /// </summary>
-        public static bool EnableIDynamicInterfaceCastableSupport
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get => GetConfigurationValue(EnableIDynamicInterfaceCastableSupportPropertyName, ref _enableIDynamicInterfaceCastableSupport, true);
-        }
-
+        public static bool EnableIDynamicInterfaceCastableSupport
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(EnableIDynamicInterfaceCastableSupportPropertyName, ref _enableIDynamicInterfaceCastableSupport, true);
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether to project .NET types to their <c>Windows.UI.Xaml</c> equivalents instead of their <c>Microsoft.UI.Xaml</c> equivalents.
+        /// </summary>
+        public static bool UseWindowsUIXamlProjections
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => GetConfigurationValue(UseWindowsUIXamlProjectionsPropertyName, ref _useWindowsUIXamlProjections, false);
+        }
+
         /// <summary>
         /// Gets a configuration value for a specified property.
         /// </summary>
         /// <param name="propertyName">The property name to retrieve the value for.</param>
         /// <param name="cachedResult">The cached result for the target configuration value.</param>
         /// <returns>The value of the specified configuration setting.</returns>
-        private static bool GetConfigurationValue(string propertyName, ref int cachedResult, bool defaultValue)
-        {
-            // The cached switch value has 3 states:
-            //   0: unknown.
-            //   1: true
-            //   -1: false
-            //
-            // This method doesn't need to worry about concurrent accesses to the cached result,
-            // as even if the configuration value is retrieved twice, that'll always be the same.
-            if (cachedResult < 0)
-            {
-                return false;
-            }
-
-            if (cachedResult > 0)
-            {
-                return true;
-            }
-
-            // Get the configuration switch value, or its default.
-            // All feature switches have a default set in the .targets file.
-            if (!AppContext.TryGetSwitch(propertyName, out bool isEnabled))
-            {
-                isEnabled = defaultValue;
-            }
-
-            // Update the cached result
-            cachedResult = isEnabled ? 1 : -1;
-
-            return isEnabled;
-        }
-    }
+        private static bool GetConfigurationValue(string propertyName, ref int cachedResult, bool defaultValue)
+        {
+            // The cached switch value has 3 states:
+            //   0: unknown.
+            //   1: true
+            //   -1: false
+            //
+            // This method doesn't need to worry about concurrent accesses to the cached result,
+            // as even if the configuration value is retrieved twice, that'll always be the same.
+            if (cachedResult < 0)
+            {
+                return false;
+            }
+
+            if (cachedResult > 0)
+            {
+                return true;
+            }
+
+            // Get the configuration switch value, or its default.
+            // All feature switches have a default set in the .targets file.
+            if (!AppContext.TryGetSwitch(propertyName, out bool isEnabled))
+            {
+                isEnabled = defaultValue;
+            }
+
+            // Update the cached result
+            cachedResult = isEnabled ? 1 : -1;
+
+            return isEnabled;
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/WinRT.Runtime/Configuration/ILLink.Substitutions.xml b/src/WinRT.Runtime/Configuration/ILLink.Substitutions.xml
index 8a04a92b3..c962b9db2 100644
--- a/src/WinRT.Runtime/Configuration/ILLink.Substitutions.xml
+++ b/src/WinRT.Runtime/Configuration/ILLink.Substitutions.xml
@@ -25,6 +25,10 @@
       <!-- CSWINRT_ENABLE_IDYNAMICINTERFACECASTABLE switch -->
       <method signature="System.Boolean get_EnableIDynamicInterfaceCastableSupport()" body="stub" value="false" feature="CSWINRT_ENABLE_IDYNAMICINTERFACECASTABLE" featurevalue="false"/>
       <method signature="System.Boolean get_EnableIDynamicInterfaceCastableSupport()" body="stub" value="true" feature="CSWINRT_ENABLE_IDYNAMICINTERFACECASTABLE" featurevalue="true"/>
+
+      <!-- CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS switch -->
+      <method signature="System.Boolean get_UseWindowsUIXamlProjections()" body="stub" value="false" feature="CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS" featurevalue="false" />
+      <method signature="System.Boolean get_UseWindowsUIXamlProjections()" body="stub" value="true" feature="CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS" featurevalue="true" />
     </type>
   </assembly>
 
diff --git a/src/WinRT.Runtime/GuidGenerator.cs b/src/WinRT.Runtime/GuidGenerator.cs
index b02f767ad..b8514f537 100644
--- a/src/WinRT.Runtime/GuidGenerator.cs
+++ b/src/WinRT.Runtime/GuidGenerator.cs
@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation.
+// Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
 using System;
@@ -7,6 +7,7 @@
 using System.Runtime.CompilerServices;
 using System.Security.Cryptography;
 using System.Text;
+using WinRT.Interop;
 
 namespace WinRT
 {
@@ -22,7 +23,19 @@ static class GuidGenerator
 #endif
         public static Guid GetGUID(Type type)
         {
-            return type.GetGuidType().GUID;
+            type = type.GetGuidType();
+
+            // Only check the WUX/MUX types if the feature switch is set, to avoid introducing
+            // performance regressions in the standard case where MUX is targeted (default).
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                if (TryGetWindowsUIXamlIID(type, out Guid iid))
+                {
+                    return iid;
+                }
+            }
+
+            return type.GUID;
         }
 
         public static Guid GetIID(
@@ -32,6 +45,16 @@ public static Guid GetIID(
             Type type)
         {
             type = type.GetGuidType();
+
+            // Same optional check as above
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                if (TryGetWindowsUIXamlIID(type, out Guid iid))
+                {
+                    return iid;
+                }
+            }
+
             if (!type.IsGenericType)
             {
                 return type.GUID;
@@ -39,6 +62,48 @@ public static Guid GetIID(
             return (Guid)type.GetField("PIID").GetValue(null);
         }
 
+        internal static bool TryGetWindowsUIXamlIID(Type type, out Guid iid)
+        {
+            if (type == typeof(global::ABI.System.Collections.Specialized.INotifyCollectionChanged))
+            {
+                iid = IID.IID_WUX_INotifyCollectionChanged;
+
+                return true;
+            }
+
+            if (type == typeof(global::ABI.System.ComponentModel.INotifyPropertyChanged))
+            {
+                iid = IID.IID_WUX_INotifyPropertyChanged;
+
+                return true;
+            }
+
+            if (type == typeof(global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs))
+            {
+                iid = IID.IID_WUX_INotifyCollectionChangedEventArgs;
+
+                return true;
+            }
+
+            if (type == typeof(global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler))
+            {
+                iid = IID.IID_WUX_NotifyCollectionChangedEventHandler;
+
+                return true;
+            }
+
+            if (type == typeof(global::ABI.System.ComponentModel.PropertyChangedEventHandler))
+            {
+                iid = IID.IID_WUX_PropertyChangedEventHandler;
+
+                return true;
+            }
+
+            iid = default;
+
+            return false;
+        }
+
         public static string GetSignature(
 #if NET
             // This '[DynamicallyAccessedMembers]' annotation is here just for backwards-compatibility with old projections. Those are
diff --git a/src/WinRT.Runtime/Interop/IID.g.cs b/src/WinRT.Runtime/Interop/IID.g.cs
index 94d2a90d7..1929b3cd8 100644
--- a/src/WinRT.Runtime/Interop/IID.g.cs
+++ b/src/WinRT.Runtime/Interop/IID.g.cs
@@ -440,8 +440,108 @@ internal static ref readonly Guid IID_IRestrictedErrorInfo
             }
         }
 
-        /// <summary>The IID for <c>INotifyCollectionChangedEventArgsFactory</c> (5108EBA4-4892-5A20-8374-A96815E0FD27).</summary>
-        internal static ref readonly Guid IID_INotifyCollectionChangedEventArgsFactory
+        /// <summary>The IID for <c>MUX_INotifyPropertyChanged</c> (90B17601-B065-586E-83D9-9ADC3A695284).</summary>
+        internal static ref readonly Guid IID_MUX_INotifyPropertyChanged
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x01, 0x76, 0xB1, 0x90,
+                    0x65, 0xB0,
+                    0x6E, 0x58,
+                    0x83,
+                    0xD9,
+                    0x9A,
+                    0xDC,
+                    0x3A,
+                    0x69,
+                    0x52,
+                    0x84
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>WUX_INotifyPropertyChanged</c> (CF75D69C-F2F4-486B-B302-BB4C09BAEBFA).</summary>
+        internal static ref readonly Guid IID_WUX_INotifyPropertyChanged
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x9C, 0xD6, 0x75, 0xCF,
+                    0xF4, 0xF2,
+                    0x6B, 0x48,
+                    0xB3,
+                    0x02,
+                    0xBB,
+                    0x4C,
+                    0x09,
+                    0xBA,
+                    0xEB,
+                    0xFA
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>MUX_INotifyCollectionChanged</c> (530155E1-28A5-5693-87CE-30724D95A06D).</summary>
+        internal static ref readonly Guid IID_MUX_INotifyCollectionChanged
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0xE1, 0x55, 0x01, 0x53,
+                    0xA5, 0x28,
+                    0x93, 0x56,
+                    0x87,
+                    0xCE,
+                    0x30,
+                    0x72,
+                    0x4D,
+                    0x95,
+                    0xA0,
+                    0x6D
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>WUX_INotifyCollectionChanged</c> (28B167D5-1A31-465B-9B25-D5C3AE686C40).</summary>
+        internal static ref readonly Guid IID_WUX_INotifyCollectionChanged
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0xD5, 0x67, 0xB1, 0x28,
+                    0x31, 0x1A,
+                    0x5B, 0x46,
+                    0x9B,
+                    0x25,
+                    0xD5,
+                    0xC3,
+                    0xAE,
+                    0x68,
+                    0x6C,
+                    0x40
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>MUX_INotifyCollectionChangedEventArgsFactory</c> (5108EBA4-4892-5A20-8374-A96815E0FD27).</summary>
+        internal static ref readonly Guid IID_MUX_INotifyCollectionChangedEventArgsFactory
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]   
             get
@@ -465,8 +565,33 @@ internal static ref readonly Guid IID_INotifyCollectionChangedEventArgsFactory
             }
         }
 
-        /// <summary>The IID for <c>INotifyCollectionChangedEventArgs</c> (DA049FF2-D2E0-5FE8-8C7B-F87F26060B6F).</summary>
-        internal static ref readonly Guid IID_INotifyCollectionChangedEventArgs
+        /// <summary>The IID for <c>WUX_INotifyCollectionChangedEventArgsFactory</c> (B30C3E3A-DF8D-44A5-9A38-7AC0D08CE63D).</summary>
+        internal static ref readonly Guid IID_WUX_INotifyCollectionChangedEventArgsFactory
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x3A, 0x3E, 0x0C, 0xB3,
+                    0x8D, 0xDF,
+                    0xA5, 0x44,
+                    0x9A,
+                    0x38,
+                    0x7A,
+                    0xC0,
+                    0xD0,
+                    0x8C,
+                    0xE6,
+                    0x3D
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>MUX_INotifyCollectionChangedEventArgs</c> (DA049FF2-D2E0-5FE8-8C7B-F87F26060B6F).</summary>
+        internal static ref readonly Guid IID_MUX_INotifyCollectionChangedEventArgs
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]   
             get
@@ -490,8 +615,83 @@ internal static ref readonly Guid IID_INotifyCollectionChangedEventArgs
             }
         }
 
-        /// <summary>The IID for <c>PropertyChangedEventArgsRuntimeClassFactory</c> (7C0C27A8-0B41-5070-B160-FC9AE960A36C).</summary>
-        internal static ref readonly Guid IID_PropertyChangedEventArgsRuntimeClassFactory
+        /// <summary>The IID for <c>WUX_INotifyCollectionChangedEventArgs</c> (4CF68D33-E3F2-4964-B85E-945B4F7E2F21).</summary>
+        internal static ref readonly Guid IID_WUX_INotifyCollectionChangedEventArgs
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x33, 0x8D, 0xF6, 0x4C,
+                    0xF2, 0xE3,
+                    0x64, 0x49,
+                    0xB8,
+                    0x5E,
+                    0x94,
+                    0x5B,
+                    0x4F,
+                    0x7E,
+                    0x2F,
+                    0x21
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>WUX_MotifyCollectionChangedEventHandler</c> (8B0909DC-2005-5D93-BF8A-725F017BAA8D).</summary>
+        internal static ref readonly Guid IID_MUX_NotifyCollectionChangedEventHandler
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0xDC, 0x09, 0x09, 0x8B,
+                    0x05, 0x20,
+                    0x93, 0x5D,
+                    0xBF,
+                    0x8A,
+                    0x72,
+                    0x5F,
+                    0x01,
+                    0x7B,
+                    0xAA,
+                    0x8D
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>WUX_NotifyCollectionChangedEventHandler</c> (CA10B37C-F382-4591-8557-5E24965279B0).</summary>
+        internal static ref readonly Guid IID_WUX_NotifyCollectionChangedEventHandler
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x7C, 0xB3, 0x10, 0xCA,
+                    0x82, 0xF3,
+                    0x91, 0x45,
+                    0x85,
+                    0x57,
+                    0x5E,
+                    0x24,
+                    0x96,
+                    0x52,
+                    0x79,
+                    0xB0
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>MUX_PropertyChangedEventArgsRuntimeClassFactory</c> (7C0C27A8-0B41-5070-B160-FC9AE960A36C).</summary>
+        internal static ref readonly Guid IID_MUX_PropertyChangedEventArgsRuntimeClassFactory
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]   
             get
@@ -515,6 +715,81 @@ internal static ref readonly Guid IID_PropertyChangedEventArgsRuntimeClassFactor
             }
         }
 
+        /// <summary>The IID for <c>WUX_PropertyChangedEventArgsRuntimeClassFactory</c> (6DCC9C03-E0C7-4EEE-8EA9-37E3406EEB1C).</summary>
+        internal static ref readonly Guid IID_WUX_PropertyChangedEventArgsRuntimeClassFactory
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x03, 0x9C, 0xCC, 0x6D,
+                    0xC7, 0xE0,
+                    0xEE, 0x4E,
+                    0x8E,
+                    0xA9,
+                    0x37,
+                    0xE3,
+                    0x40,
+                    0x6E,
+                    0xEB,
+                    0x1C
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>MUX_PropertyChangedEventHandler</c> (E3DE52F6-1E32-5DA6-BB2D-B5B6096C962D).</summary>
+        internal static ref readonly Guid IID_MUX_PropertyChangedEventHandler
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0xF6, 0x52, 0xDE, 0xE3,
+                    0x32, 0x1E,
+                    0xA6, 0x5D,
+                    0xBB,
+                    0x2D,
+                    0xB5,
+                    0xB6,
+                    0x09,
+                    0x6C,
+                    0x96,
+                    0x2D
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
+        /// <summary>The IID for <c>WUX_PropertyChangedEventHandler</c> (50F19C16-0A22-4D8E-A089-1EA9951657D2).</summary>
+        internal static ref readonly Guid IID_WUX_PropertyChangedEventHandler
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
+            get
+            {
+                ReadOnlySpan<byte> data = new byte[]
+                {
+                    0x16, 0x9C, 0xF1, 0x50,
+                    0x22, 0x0A,
+                    0x8E, 0x4D,
+                    0xA0,
+                    0x89,
+                    0x1E,
+                    0xA9,
+                    0x95,
+                    0x16,
+                    0x57,
+                    0xD2
+                };
+
+                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
+            }
+        }
+
         /// <summary>The IID for <c>DataErrorsChangedEventArgsRuntimeClassFactory</c> (62D0BD1E-B85F-5FCC-842A-7CB0DDA37FE5).</summary>
         internal static ref readonly Guid IID_DataErrorsChangedEventArgsRuntimeClassFactory
         {
@@ -590,56 +865,6 @@ internal static ref readonly Guid IID_INotifyDataErrorInfo
             }
         }
 
-        /// <summary>The IID for <c>INotifyPropertyChanged</c> (90B17601-B065-586E-83D9-9ADC3A695284).</summary>
-        internal static ref readonly Guid IID_INotifyPropertyChanged
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
-            get
-            {
-                ReadOnlySpan<byte> data = new byte[]
-                {
-                    0x01, 0x76, 0xB1, 0x90,
-                    0x65, 0xB0,
-                    0x6E, 0x58,
-                    0x83,
-                    0xD9,
-                    0x9A,
-                    0xDC,
-                    0x3A,
-                    0x69,
-                    0x52,
-                    0x84
-                };
-
-                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
-            }
-        }
-
-        /// <summary>The IID for <c>INotifyCollectionChanged</c> (530155E1-28A5-5693-87CE-30724D95A06D).</summary>
-        internal static ref readonly Guid IID_INotifyCollectionChanged
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
-            get
-            {
-                ReadOnlySpan<byte> data = new byte[]
-                {
-                    0xE1, 0x55, 0x01, 0x53,
-                    0xA5, 0x28,
-                    0x93, 0x56,
-                    0x87,
-                    0xCE,
-                    0x30,
-                    0x72,
-                    0x4D,
-                    0x95,
-                    0xA0,
-                    0x6D
-                };
-
-                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
-            }
-        }
-
         /// <summary>The IID for <c>ICommand</c> (E5AF3542-CA67-4081-995B-709DD13792DF).</summary>
         internal static ref readonly Guid IID_ICommand
         {
@@ -690,56 +915,6 @@ internal static ref readonly Guid IID_IGlobalInterfaceTable
             }
         }
 
-        /// <summary>The IID for <c>PropertyChangedEventHandler</c> (E3DE52F6-1E32-5DA6-BB2D-B5B6096C962D).</summary>
-        internal static ref readonly Guid IID_PropertyChangedEventHandler
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
-            get
-            {
-                ReadOnlySpan<byte> data = new byte[]
-                {
-                    0xF6, 0x52, 0xDE, 0xE3,
-                    0x32, 0x1E,
-                    0xA6, 0x5D,
-                    0xBB,
-                    0x2D,
-                    0xB5,
-                    0xB6,
-                    0x09,
-                    0x6C,
-                    0x96,
-                    0x2D
-                };
-
-                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
-            }
-        }
-
-        /// <summary>The IID for <c>NotifyCollectionChangedEventHandler</c> (8B0909DC-2005-5D93-BF8A-725F017BAA8D).</summary>
-        internal static ref readonly Guid IID_NotifyCollectionChangedEventHandler
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]   
-            get
-            {
-                ReadOnlySpan<byte> data = new byte[]
-                {
-                    0xDC, 0x09, 0x09, 0x8B,
-                    0x05, 0x20,
-                    0x93, 0x5D,
-                    0xBF,
-                    0x8A,
-                    0x72,
-                    0x5F,
-                    0x01,
-                    0x7B,
-                    0xAA,
-                    0x8D
-                };
-
-                return ref Unsafe.As<byte, Guid>(ref MemoryMarshal.GetReference(data));
-            }
-        }
-
         /// <summary>The IID for <c>EventHandler</c> (C50898F6-C536-5F47-8583-8B2C2438A13B).</summary>
         internal static ref readonly Guid IID_EventHandler
         {
diff --git a/src/WinRT.Runtime/Interop/IID.tt b/src/WinRT.Runtime/Interop/IID.tt
index 47e4fc3a9..17d48ca84 100644
--- a/src/WinRT.Runtime/Interop/IID.tt
+++ b/src/WinRT.Runtime/Interop/IID.tt
@@ -39,18 +39,25 @@ var entries = new (string Name, string IID, bool IsPublic)[]
     ("ISupportErrorInfo", "DF0B3D60-548F-101B-8E65-08002B2BD119", false),
     ("ILanguageExceptionErrorInfo", "04A2DBF3-DF83-116C-0946-0812ABF6E07D", false),
     ("IRestrictedErrorInfo", "82BA7092-4C88-427D-A7BC-16DD93FEB67E", false),
-    ("INotifyCollectionChangedEventArgsFactory", "5108EBA4-4892-5A20-8374-A96815E0FD27", false),
-    ("INotifyCollectionChangedEventArgs", "DA049FF2-D2E0-5FE8-8C7B-F87F26060B6F", false),
-    ("PropertyChangedEventArgsRuntimeClassFactory", "7C0C27A8-0B41-5070-B160-FC9AE960A36C", false),
+    ("MUX_INotifyPropertyChanged", "90B17601-B065-586E-83D9-9ADC3A695284", false),
+    ("WUX_INotifyPropertyChanged", "CF75D69C-F2F4-486B-B302-BB4C09BAEBFA", false),
+    ("MUX_INotifyCollectionChanged", "530155E1-28A5-5693-87CE-30724D95A06D", false),
+    ("WUX_INotifyCollectionChanged", "28B167D5-1A31-465B-9B25-D5C3AE686C40", false),
+    ("MUX_INotifyCollectionChangedEventArgsFactory", "5108EBA4-4892-5A20-8374-A96815E0FD27", false),
+    ("WUX_INotifyCollectionChangedEventArgsFactory", "B30C3E3A-DF8D-44A5-9A38-7AC0D08CE63D", false),
+    ("MUX_INotifyCollectionChangedEventArgs", "DA049FF2-D2E0-5FE8-8C7B-F87F26060B6F", false),
+    ("WUX_INotifyCollectionChangedEventArgs", "4CF68D33-E3F2-4964-B85E-945B4F7E2F21", false),
+    ("MUX_NotifyCollectionChangedEventHandler", "8B0909DC-2005-5D93-BF8A-725F017BAA8D", false),
+    ("WUX_NotifyCollectionChangedEventHandler", "CA10B37C-F382-4591-8557-5E24965279B0", false),
+    ("MUX_PropertyChangedEventArgsRuntimeClassFactory", "7C0C27A8-0B41-5070-B160-FC9AE960A36C", false),
+    ("WUX_PropertyChangedEventArgsRuntimeClassFactory", "6DCC9C03-E0C7-4EEE-8EA9-37E3406EEB1C", false),
+    ("MUX_PropertyChangedEventHandler", "E3DE52F6-1E32-5DA6-BB2D-B5B6096C962D", false),
+    ("WUX_PropertyChangedEventHandler", "50F19C16-0A22-4D8E-A089-1EA9951657D2", false),
     ("DataErrorsChangedEventArgsRuntimeClassFactory", "62D0BD1E-B85F-5FCC-842A-7CB0DDA37FE5", false),
     ("UriRuntimeClassFactory", "44A9796F-723E-4FDF-A218-033E75B0C084", false),
     ("INotifyDataErrorInfo", "0EE6C2CC-273E-567D-BC0A-1DD87EE51EBA", false),
-    ("INotifyPropertyChanged", "90B17601-B065-586E-83D9-9ADC3A695284", false),
-    ("INotifyCollectionChanged", "530155E1-28A5-5693-87CE-30724D95A06D", false),
     ("ICommand", "E5AF3542-CA67-4081-995B-709DD13792DF", false),
     ("IGlobalInterfaceTable", "00000146-0000-0000-C000-000000000046", false),
-    ("PropertyChangedEventHandler", "E3DE52F6-1E32-5DA6-BB2D-B5B6096C962D", false),
-    ("NotifyCollectionChangedEventHandler", "8B0909DC-2005-5D93-BF8A-725F017BAA8D", false),
     ("EventHandler", "C50898F6-C536-5F47-8583-8B2C2438A13B", false),
     ("IBindableVectorView", "346DD6E7-976E-4BC3-815D-ECE243BC0F33", false),
     ("IEnumerable", "036D2C08-DF29-41AF-8AA2-D774BE62BA6F", false),
diff --git a/src/WinRT.Runtime/Interop/WuxMuxProjectedTypeAttribute.cs b/src/WinRT.Runtime/Interop/WuxMuxProjectedTypeAttribute.cs
new file mode 100644
index 000000000..3f56b6dc7
--- /dev/null
+++ b/src/WinRT.Runtime/Interop/WuxMuxProjectedTypeAttribute.cs
@@ -0,0 +1,17 @@
+using System;
+
+namespace WinRT.Interop
+{
+    // This attribute is only used by the IIDOptimizer for resolving the signature of a type that has different
+    // IIDs on WUX/MUX targets. The actual IIDs are hardcoded in WinRT.Runtime, so they are not needed here.
+    // TODO: remove this entirely when either IIDOptimizer is removed, or when the option to hardcode IIDs is added.
+
+    /// <summary>
+    /// This type signals that the type it is applied to is projected into .NET from either a Windows.UI.Xaml type or a Microsoft.UI.Xaml type.
+    /// For this type, the GuidAttribute is not used and instead the GetGuidSignature method must be called to get the IID or generic IID signature part of the type.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+    internal sealed class WuxMuxProjectedTypeAttribute : Attribute
+    {
+    }
+}
diff --git a/src/WinRT.Runtime/MatchingRefApiCompatBaseline.txt b/src/WinRT.Runtime/MatchingRefApiCompatBaseline.txt
index 4040efbcc..1276f8957 100644
--- a/src/WinRT.Runtime/MatchingRefApiCompatBaseline.txt
+++ b/src/WinRT.Runtime/MatchingRefApiCompatBaseline.txt
@@ -232,6 +232,9 @@ CannotRemoveAttribute : Attribute 'System.Diagnostics.CodeAnalysis.Unconditional
 CannotRemoveAttribute : Attribute 'System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute' exists on 'ABI.WinRT.Interop.IActivationFactory.AsInterface<I>()' in the implementation but not the reference.
 CannotRemoveAttribute : Attribute 'System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute' exists on 'WinRT.IInspectable.As<I>()' in the implementation but not the reference.
 CannotRemoveAttribute : Attribute 'System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute' exists on 'WinRT.TypeExtensions.FindHelperType(System.Type)' in the implementation but not the reference.
+CannotRemoveAttribute : Attribute 'WinRT.Interop.WuxMuxProjectedTypeAttribute' exists on 'ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler' in the implementation but not the reference.
+CannotRemoveAttribute : Attribute 'WinRT.Interop.WuxMuxProjectedTypeAttribute' exists on 'ABI.System.ComponentModel.PropertyChangedEventHandler' in the implementation but not the reference.
+CannotRemoveAttribute : Attribute 'WinRT.Interop.WuxMuxProjectedTypeAttribute' exists on 'ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs' in the implementation but not the reference.
 TypesMustExist : Type 'WinRT.WinRTRuntimeClassNameAttribute' does not exist in the reference but it does exist in the implementation.
 MembersMustExist : Member 'public void WinRT.ComWrappersSupport.RegisterTypeRuntimeClassNameLookup(System.Func<System.Type, System.String>)' does not exist in the reference but it does exist in the implementation.
 CannotRemoveAttribute : Attribute 'System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute' exists on 'WinRT.Projections.FindCustomHelperTypeMapping(System.Type, System.Boolean)' in the implementation but not the reference.
@@ -264,4 +267,4 @@ MembersMustExist : Member 'public void WinRT.ComWrappersHelper.Init(System.Boole
 MembersMustExist : Member 'public System.Guid ABI.System.EventHandler<T>.IID.get()' does not exist in the reference but it does exist in the implementation.
 MembersMustExist : Member 'public System.Guid ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler.IID.get()' does not exist in the reference but it does exist in the implementation.
 MembersMustExist : Member 'public System.Guid ABI.System.ComponentModel.PropertyChangedEventHandler.IID.get()' does not exist in the reference but it does exist in the implementation.
-Total Issues: 265
+Total Issues: 268
diff --git a/src/WinRT.Runtime/Projections.CustomTypeMappings.g.cs b/src/WinRT.Runtime/Projections.CustomTypeMappings.g.cs
index a45d5e0e8..86e3658ec 100644
--- a/src/WinRT.Runtime/Projections.CustomTypeMappings.g.cs
+++ b/src/WinRT.Runtime/Projections.CustomTypeMappings.g.cs
@@ -506,6 +506,11 @@ public static void RegisterDataErrorsChangedEventArgsMapping()
                 return;
             }
 
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                throw new NotSupportedException("The 'DataErrorsChangedEventArgs' type is only supported for WinUI, and not when using System XAML projections (make sure the 'CsWinRTUseWindowsUIXamlProjections' property is not set to 'true').");
+            }
+
             if (Interlocked.CompareExchange(ref _DataErrorsChangedEventArgs, 1, 0) == 1)
             {
                 return;
@@ -531,11 +536,22 @@ public static void RegisterPropertyChangedEventArgsMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(PropertyChangedEventArgs),
-                typeof(ABI.System.ComponentModel.PropertyChangedEventArgs),
-                "Microsoft.UI.Xaml.Data.PropertyChangedEventArgs",
-                isRuntimeClass: true);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(PropertyChangedEventArgs),
+                    typeof(ABI.System.ComponentModel.PropertyChangedEventArgs),
+                    "Windows.UI.Xaml.Data.PropertyChangedEventArgs",
+                    isRuntimeClass: true);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(PropertyChangedEventArgs),
+                    typeof(ABI.System.ComponentModel.PropertyChangedEventArgs),
+                    "Microsoft.UI.Xaml.Data.PropertyChangedEventArgs",
+                    isRuntimeClass: true);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Data.PropertyChangedEventHandler"</c> WinRT type.</summary>
@@ -551,11 +567,22 @@ public static void RegisterPropertyChangedEventHandlerMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(PropertyChangedEventHandler),
-                typeof(ABI.System.ComponentModel.PropertyChangedEventHandler),
-                "Microsoft.UI.Xaml.Data.PropertyChangedEventHandler",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(PropertyChangedEventHandler),
+                    typeof(ABI.System.ComponentModel.PropertyChangedEventHandler),
+                    "Windows.UI.Xaml.Data.PropertyChangedEventHandler",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(PropertyChangedEventHandler),
+                    typeof(ABI.System.ComponentModel.PropertyChangedEventHandler),
+                    "Microsoft.UI.Xaml.Data.PropertyChangedEventHandler",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Data.INotifyDataErrorInfo"</c> WinRT type.</summary>
@@ -566,6 +593,11 @@ public static void RegisterINotifyDataErrorInfoMapping()
                 return;
             }
 
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                throw new NotSupportedException("The 'INotifyDataErrorInfo' type is only supported for WinUI, and not when using System XAML projections (make sure the 'CsWinRTUseWindowsUIXamlProjections' property is not set to 'true').");
+            }
+
             if (Interlocked.CompareExchange(ref _INotifyDataErrorInfo, 1, 0) == 1)
             {
                 return;
@@ -591,11 +623,22 @@ public static void RegisterINotifyPropertyChangedMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(INotifyPropertyChanged),
-                typeof(ABI.System.ComponentModel.INotifyPropertyChanged),
-                "Microsoft.UI.Xaml.Data.INotifyPropertyChanged",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(INotifyPropertyChanged),
+                    typeof(ABI.System.ComponentModel.INotifyPropertyChanged),
+                    "Windows.UI.Xaml.Data.INotifyPropertyChanged",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(INotifyPropertyChanged),
+                    typeof(ABI.System.ComponentModel.INotifyPropertyChanged),
+                    "Microsoft.UI.Xaml.Data.INotifyPropertyChanged",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Interop.ICommand"</c> WinRT type.</summary>
@@ -611,11 +654,22 @@ public static void RegisterICommandMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(ICommand),
-                typeof(ABI.System.Windows.Input.ICommand),
-                "Microsoft.UI.Xaml.Interop.ICommand",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(ICommand),
+                    typeof(ABI.System.Windows.Input.ICommand),
+                    "Windows.UI.Xaml.Interop.ICommand",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(ICommand),
+                    typeof(ABI.System.Windows.Input.ICommand),
+                    "Microsoft.UI.Xaml.Interop.ICommand",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.IXamlServiceProvider"</c> WinRT type.</summary>
@@ -626,6 +680,11 @@ public static void RegisterIServiceProviderMapping()
                 return;
             }
 
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                throw new NotSupportedException("The 'IServiceProvider' type is only supported for WinUI, and not when using System XAML projections (make sure the 'CsWinRTUseWindowsUIXamlProjections' property is not set to 'true').");
+            }
+
             if (Interlocked.CompareExchange(ref _IServiceProvider, 1, 0) == 1)
             {
                 return;
@@ -831,11 +890,22 @@ public static void RegisterIEnumerableMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(IEnumerable),
-                typeof(ABI.System.Collections.IEnumerable),
-                "Microsoft.UI.Xaml.Interop.IBindableIterable",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(IEnumerable),
+                    typeof(ABI.System.Collections.IEnumerable),
+                    "Windows.UI.Xaml.Interop.IBindableIterable",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(IEnumerable),
+                    typeof(ABI.System.Collections.IEnumerable),
+                    "Microsoft.UI.Xaml.Interop.IBindableIterable",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Interop.IBindableVector"</c> WinRT type.</summary>
@@ -851,11 +921,22 @@ public static void RegisterIListMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(IList),
-                typeof(ABI.System.Collections.IList),
-                "Microsoft.UI.Xaml.Interop.IBindableVector",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(IList),
+                    typeof(ABI.System.Collections.IList),
+                    "Windows.UI.Xaml.Interop.IBindableVector",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(IList),
+                    typeof(ABI.System.Collections.IList),
+                    "Microsoft.UI.Xaml.Interop.IBindableVector",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Interop.INotifyCollectionChanged"</c> WinRT type.</summary>
@@ -871,11 +952,22 @@ public static void RegisterINotifyCollectionChangedMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(INotifyCollectionChanged),
-                typeof(ABI.System.Collections.Specialized.INotifyCollectionChanged),
-                "Microsoft.UI.Xaml.Interop.INotifyCollectionChanged",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(INotifyCollectionChanged),
+                    typeof(ABI.System.Collections.Specialized.INotifyCollectionChanged),
+                    "Windows.UI.Xaml.Interop.INotifyCollectionChanged",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(INotifyCollectionChanged),
+                    typeof(ABI.System.Collections.Specialized.INotifyCollectionChanged),
+                    "Microsoft.UI.Xaml.Interop.INotifyCollectionChanged",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction"</c> WinRT type.</summary>
@@ -891,11 +983,22 @@ public static void RegisterNotifyCollectionChangedActionMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(NotifyCollectionChangedAction),
-                typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedAction),
-                "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(NotifyCollectionChangedAction),
+                    typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedAction),
+                    "Windows.UI.Xaml.Interop.NotifyCollectionChangedAction",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(NotifyCollectionChangedAction),
+                    typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedAction),
+                    "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs"</c> WinRT type.</summary>
@@ -911,11 +1014,22 @@ public static void RegisterNotifyCollectionChangedEventArgsMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(NotifyCollectionChangedEventArgs),
-                typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs),
-                "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs",
-                isRuntimeClass: true);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(NotifyCollectionChangedEventArgs),
+                    typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs),
+                    "Windows.UI.Xaml.Interop.NotifyCollectionChangedEventArgs",
+                    isRuntimeClass: true);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(NotifyCollectionChangedEventArgs),
+                    typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs),
+                    "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs",
+                    isRuntimeClass: true);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventHandler"</c> WinRT type.</summary>
@@ -931,11 +1045,22 @@ public static void RegisterNotifyCollectionChangedEventHandlerMapping()
                 return;
             }
 
-            RegisterCustomAbiTypeMapping(
-                typeof(NotifyCollectionChangedEventHandler),
-                typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler),
-                "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventHandler",
-                isRuntimeClass: false);
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(NotifyCollectionChangedEventHandler),
+                    typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler),
+                    "Windows.UI.Xaml.Interop.NotifyCollectionChangedEventHandler",
+                    isRuntimeClass: false);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(NotifyCollectionChangedEventHandler),
+                    typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler),
+                    "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventHandler",
+                    isRuntimeClass: false);
+            }
         }
 
         /// <summary>Registers the custom ABI type mapping for the <c>"Windows.Foundation.Numerics.Matrix3x2"</c> WinRT type.</summary>
diff --git a/src/WinRT.Runtime/Projections.CustomTypeMappings.tt b/src/WinRT.Runtime/Projections.CustomTypeMappings.tt
index 3d244beb8..8457dc046 100644
--- a/src/WinRT.Runtime/Projections.CustomTypeMappings.tt
+++ b/src/WinRT.Runtime/Projections.CustomTypeMappings.tt
@@ -50,6 +50,21 @@ void WriteGuardStatements(string name)
             {
                 return;
             }
+<#
+
+    if (name == "DataErrorsChangedEventArgs" ||
+        name == "INotifyDataErrorInfo" ||
+        name == "IServiceProvider")
+    {
+        WriteLine("");
+#>
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                throw new NotSupportedException("The '<#=name#>' type is only supported for WinUI, and not when using System XAML projections (make sure the 'CsWinRTUseWindowsUIXamlProjections' property is not set to 'true').");
+            }
+<#
+    }
+#>
 
             if (Interlocked.CompareExchange(ref _<#=Regex.Replace(name, "[?<>,]", "_")#>, 1, 0) == 1)
             {
@@ -110,7 +125,7 @@ var registerCustomAbiTypeMappings = new (string Public, string Abi, string Name,
     ("Quaternion", "ABI.System.Numerics.Quaternion", "Windows.Foundation.Numerics.Quaternion", null, false),
     ("Vector2", "ABI.System.Numerics.Vector2", "Windows.Foundation.Numerics.Vector2", null, false),
     ("Vector3", "ABI.System.Numerics.Vector3", "Windows.Foundation.Numerics.Vector3", null, false),
-    ("Vector4", "ABI.System.Numerics.Vector4", "Windows.Foundation.Numerics.Vector4", null, false),
+    ("Vector4", "ABI.System.Numerics.Vector4", "Windows.Foundation.Numerics.Vector4", null, false)
 };
 
 // Types for 'RegisterCustomTypeToHelperTypeMapping'
@@ -126,6 +141,21 @@ var registerCustomTypeToHelperTypeMapping = new (string Public, string Helper)[]
     ("ICollection", "ABI.System.Collections.ICollection")
 };
 
+// Types that have different projections for System XAML
+var systemXamlProjectionTypeMapping = new(string Public, string Name)[]
+{
+    ("PropertyChangedEventArgs", "Windows.UI.Xaml.Data.PropertyChangedEventArgs"),
+    ("PropertyChangedEventHandler", "Windows.UI.Xaml.Data.PropertyChangedEventHandler"),
+    ("INotifyPropertyChanged", "Windows.UI.Xaml.Data.INotifyPropertyChanged"),
+    ("ICommand", "Windows.UI.Xaml.Interop.ICommand"),
+    ("IEnumerable", "Windows.UI.Xaml.Interop.IBindableIterable"),
+    ("IList", "Windows.UI.Xaml.Interop.IBindableVector"),
+    ("INotifyCollectionChanged", "Windows.UI.Xaml.Interop.INotifyCollectionChanged"),
+    ("NotifyCollectionChangedAction", "Windows.UI.Xaml.Interop.NotifyCollectionChangedAction"),
+    ("NotifyCollectionChangedEventArgs", "Windows.UI.Xaml.Interop.NotifyCollectionChangedEventArgs"),
+    ("NotifyCollectionChangedEventHandler", "Windows.UI.Xaml.Interop.NotifyCollectionChangedEventHandler")
+};
+
 // Declare all fields
 foreach (string fieldName in
     registerCustomAbiTypeMappings
@@ -145,40 +175,50 @@ foreach (var type in registerCustomAbiTypeMappings)
 {
     WriteLine("");
 
-    if (type.Name != null)
-    {
 #>
         /// <summary>Registers the custom ABI type mapping for the <c>"<#=type.Name#>"</c> WinRT type.</summary>
         public static void <#=GetMethodName(type.Public, type.Hint)#>()
         {
 <#
             WriteGuardStatements(type.Public);
-#>
+            WriteLine("");
+
+            int indexOfSystemXamlTypeMapping = Array.FindIndex(systemXamlProjectionTypeMapping, t => t.Public == type.Public);
 
+            if (indexOfSystemXamlTypeMapping != -1)
+            {
+#>
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(<#=type.Public#>),
+                    typeof(<#=type.Abi#>),
+                    "<#=systemXamlProjectionTypeMapping[indexOfSystemXamlTypeMapping].Name#>",
+                    isRuntimeClass: <#=type.IsRuntimeClass.ToString().ToLowerInvariant()#>);
+            }
+            else
+            {
+                RegisterCustomAbiTypeMapping(
+                    typeof(<#=type.Public#>),
+                    typeof(<#=type.Abi#>),
+                    "<#=type.Name#>",
+                    isRuntimeClass: <#=type.IsRuntimeClass.ToString().ToLowerInvariant()#>);
+            }
+<#
+            }
+            else
+            {
+#>
             RegisterCustomAbiTypeMapping(
                 typeof(<#=type.Public#>),
                 typeof(<#=type.Abi#>),
                 "<#=type.Name#>",
                 isRuntimeClass: <#=type.IsRuntimeClass.ToString().ToLowerInvariant()#>);
-        }
 <#
-    }
-    else
-    {
-#>
-        /// <summary>Registers the custom ABI type mapping for the <see cref="<#=type.Public#>"/> type.</summary>
-        public static void <#=GetMethodName(type.Public, type.Hint)#>()
-        {
-<#
-            WriteGuardStatements(type.Public);
+            }
 #>
-
-            RegisterCustomAbiTypeMapping(
-                typeof(<#=type.Public#>),
-                typeof(<#=type.Abi#>));
         }
 <#
-    }
 }
 
 // 'RegisterCustomTypeToHelperTypeMapping' methods
diff --git a/src/WinRT.Runtime/Projections.cs b/src/WinRT.Runtime/Projections.cs
index 734bc8f0d..21e992799 100644
--- a/src/WinRT.Runtime/Projections.cs
+++ b/src/WinRT.Runtime/Projections.cs
@@ -39,6 +39,7 @@ static Projections()
         {
             // We always register mappings for 'bool' and 'char' as they're primitive types.
             // They're also very cheap anyway and commonly used, so this keeps things simpler.
+            // This should be in sync with cswinrt/helpers.h and the reverse mapping from WinRT.SourceGenerator/TypeMapper.cs.
             RegisterCustomAbiTypeMappingNoLock(typeof(bool), typeof(ABI.System.Boolean), "Boolean");
             RegisterCustomAbiTypeMappingNoLock(typeof(char), typeof(ABI.System.Char), "Char");
 
@@ -56,6 +57,15 @@ static Projections()
             }
 #endif
 
+#if !NET
+            // Sanity check: always throw downlevel if System XAML projections are used, as this scenario is not supported.
+            // This also allows other code in WinRT.Runtime to simplify downlevel paths by just assuming this configuration.
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                throw new NotSupportedException("Using System XAML projections is only supported on modern .NET (make sure the 'CsWinRTUseWindowsUIXamlProjections' property is not set to 'true').");
+            }
+#endif
+
             // This should be in sync with cswinrt/helpers.h and the reverse mapping from WinRT.SourceGenerator/WinRTTypeWriter.cs.            
             RegisterCustomAbiTypeMappingNoLock(typeof(EventRegistrationToken), typeof(ABI.WinRT.EventRegistrationToken), "Windows.Foundation.EventRegistrationToken");
             
@@ -65,13 +75,37 @@ static Projections()
             RegisterCustomAbiTypeMappingNoLock(typeof(Exception), typeof(ABI.System.Exception), "Windows.Foundation.HResult");
             RegisterCustomAbiTypeMappingNoLock(typeof(TimeSpan), typeof(ABI.System.TimeSpan), "Windows.Foundation.TimeSpan");
             RegisterCustomAbiTypeMappingNoLock(typeof(Uri), typeof(ABI.System.Uri), "Windows.Foundation.Uri", isRuntimeClass: true);
-            RegisterCustomAbiTypeMappingNoLock(typeof(DataErrorsChangedEventArgs), typeof(ABI.System.ComponentModel.DataErrorsChangedEventArgs), "Microsoft.UI.Xaml.Data.DataErrorsChangedEventArgs", isRuntimeClass: true);
-            RegisterCustomAbiTypeMappingNoLock(typeof(PropertyChangedEventArgs), typeof(ABI.System.ComponentModel.PropertyChangedEventArgs), "Microsoft.UI.Xaml.Data.PropertyChangedEventArgs", isRuntimeClass: true);
-            RegisterCustomAbiTypeMappingNoLock(typeof(PropertyChangedEventHandler), typeof(ABI.System.ComponentModel.PropertyChangedEventHandler), "Microsoft.UI.Xaml.Data.PropertyChangedEventHandler");
-            RegisterCustomAbiTypeMappingNoLock(typeof(INotifyDataErrorInfo), typeof(ABI.System.ComponentModel.INotifyDataErrorInfo), "Microsoft.UI.Xaml.Data.INotifyDataErrorInfo");    
-            RegisterCustomAbiTypeMappingNoLock(typeof(INotifyPropertyChanged), typeof(ABI.System.ComponentModel.INotifyPropertyChanged), "Microsoft.UI.Xaml.Data.INotifyPropertyChanged");
-            RegisterCustomAbiTypeMappingNoLock(typeof(ICommand), typeof(ABI.System.Windows.Input.ICommand), "Microsoft.UI.Xaml.Input.ICommand");
-            RegisterCustomAbiTypeMappingNoLock(typeof(IServiceProvider), typeof(ABI.System.IServiceProvider), "Microsoft.UI.Xaml.IXamlServiceProvider");
+
+            if (!FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                RegisterCustomAbiTypeMappingNoLock(typeof(DataErrorsChangedEventArgs), typeof(ABI.System.ComponentModel.DataErrorsChangedEventArgs), "Microsoft.UI.Xaml.Data.DataErrorsChangedEventArgs", isRuntimeClass: true);
+                RegisterCustomAbiTypeMappingNoLock(typeof(PropertyChangedEventArgs), typeof(ABI.System.ComponentModel.PropertyChangedEventArgs), "Microsoft.UI.Xaml.Data.PropertyChangedEventArgs", isRuntimeClass: true);
+                RegisterCustomAbiTypeMappingNoLock(typeof(PropertyChangedEventHandler), typeof(ABI.System.ComponentModel.PropertyChangedEventHandler), "Microsoft.UI.Xaml.Data.PropertyChangedEventHandler");
+                RegisterCustomAbiTypeMappingNoLock(typeof(INotifyDataErrorInfo), typeof(ABI.System.ComponentModel.INotifyDataErrorInfo), "Microsoft.UI.Xaml.Data.INotifyDataErrorInfo");    
+                RegisterCustomAbiTypeMappingNoLock(typeof(INotifyPropertyChanged), typeof(ABI.System.ComponentModel.INotifyPropertyChanged), "Microsoft.UI.Xaml.Data.INotifyPropertyChanged");
+                RegisterCustomAbiTypeMappingNoLock(typeof(ICommand), typeof(ABI.System.Windows.Input.ICommand), "Microsoft.UI.Xaml.Input.ICommand");
+                RegisterCustomAbiTypeMappingNoLock(typeof(IServiceProvider), typeof(ABI.System.IServiceProvider), "Microsoft.UI.Xaml.IXamlServiceProvider");
+                RegisterCustomAbiTypeMappingNoLock(typeof(IEnumerable), typeof(ABI.System.Collections.IEnumerable), "Microsoft.UI.Xaml.Interop.IBindableIterable");
+                RegisterCustomAbiTypeMappingNoLock(typeof(IList), typeof(ABI.System.Collections.IList), "Microsoft.UI.Xaml.Interop.IBindableVector");
+                RegisterCustomAbiTypeMappingNoLock(typeof(INotifyCollectionChanged), typeof(ABI.System.Collections.Specialized.INotifyCollectionChanged), "Microsoft.UI.Xaml.Interop.INotifyCollectionChanged");
+                RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedAction), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedAction), "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction");
+                RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedEventArgs), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs), "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", isRuntimeClass: true);
+                RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedEventHandler), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler), "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventHandler");
+            }
+            else
+            {
+                RegisterCustomAbiTypeMappingNoLock(typeof(PropertyChangedEventArgs), typeof(ABI.System.ComponentModel.PropertyChangedEventArgs), "Windows.UI.Xaml.Data.PropertyChangedEventArgs", isRuntimeClass: true);
+                RegisterCustomAbiTypeMappingNoLock(typeof(PropertyChangedEventHandler), typeof(ABI.System.ComponentModel.PropertyChangedEventHandler), "Windows.UI.Xaml.Data.PropertyChangedEventHandler");
+                RegisterCustomAbiTypeMappingNoLock(typeof(INotifyPropertyChanged), typeof(ABI.System.ComponentModel.INotifyPropertyChanged), "Windows.UI.Xaml.Data.INotifyPropertyChanged");
+                RegisterCustomAbiTypeMappingNoLock(typeof(ICommand), typeof(ABI.System.Windows.Input.ICommand), "Windows.UI.Xaml.Interop.ICommand");
+                RegisterCustomAbiTypeMappingNoLock(typeof(IEnumerable), typeof(ABI.System.Collections.IEnumerable), "Windows.UI.Xaml.Interop.IBindableIterable");
+                RegisterCustomAbiTypeMappingNoLock(typeof(IList), typeof(ABI.System.Collections.IList), "Windows.UI.Xaml.Interop.IBindableVector");
+                RegisterCustomAbiTypeMappingNoLock(typeof(INotifyCollectionChanged), typeof(ABI.System.Collections.Specialized.INotifyCollectionChanged), "Windows.UI.Xaml.Interop.INotifyCollectionChanged");
+                RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedAction), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedAction), "Windows.UI.Xaml.Interop.NotifyCollectionChangedAction");
+                RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedEventArgs), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs), "Windows.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", isRuntimeClass: true);
+                RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedEventHandler), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler), "Windows.UI.Xaml.Interop.NotifyCollectionChangedEventHandler");
+            }
+
             RegisterCustomAbiTypeMappingNoLock(typeof(EventHandler<>), typeof(ABI.System.EventHandler<>), "Windows.Foundation.EventHandler`1");
 
             RegisterCustomAbiTypeMappingNoLock(typeof(KeyValuePair<,>), typeof(ABI.System.Collections.Generic.KeyValuePair<,>), "Windows.Foundation.Collections.IKeyValuePair`2");
@@ -83,12 +117,6 @@ static Projections()
             RegisterCustomAbiTypeMappingNoLock(typeof(IReadOnlyDictionary<,>), typeof(ABI.System.Collections.Generic.IReadOnlyDictionary<,>), "Windows.Foundation.Collections.IMapView`2");
             RegisterCustomAbiTypeMappingNoLock(typeof(IDisposable), typeof(ABI.System.IDisposable), "Windows.Foundation.IClosable");
 
-            RegisterCustomAbiTypeMappingNoLock(typeof(IEnumerable), typeof(ABI.System.Collections.IEnumerable), "Microsoft.UI.Xaml.Interop.IBindableIterable");
-            RegisterCustomAbiTypeMappingNoLock(typeof(IList), typeof(ABI.System.Collections.IList), "Microsoft.UI.Xaml.Interop.IBindableVector");
-            RegisterCustomAbiTypeMappingNoLock(typeof(INotifyCollectionChanged), typeof(ABI.System.Collections.Specialized.INotifyCollectionChanged), "Microsoft.UI.Xaml.Interop.INotifyCollectionChanged");
-            RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedAction), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedAction), "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction");
-            RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedEventArgs), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs), "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", isRuntimeClass: true);
-            RegisterCustomAbiTypeMappingNoLock(typeof(NotifyCollectionChangedEventHandler), typeof(ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler), "Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventHandler");
 
             RegisterCustomAbiTypeMappingNoLock(typeof(Matrix3x2), typeof(ABI.System.Numerics.Matrix3x2), "Windows.Foundation.Numerics.Matrix3x2");
             RegisterCustomAbiTypeMappingNoLock(typeof(Matrix4x4), typeof(ABI.System.Numerics.Matrix4x4), "Windows.Foundation.Numerics.Matrix4x4");
@@ -105,6 +133,7 @@ static Projections()
             RegisterCustomTypeToHelperTypeMappingNoLock(typeof(IVector<>), typeof(ABI.System.Collections.Generic.IList<>));
             RegisterCustomTypeToHelperTypeMappingNoLock(typeof(IMapView<,>), typeof(ABI.System.Collections.Generic.IReadOnlyDictionary<,>));
             RegisterCustomTypeToHelperTypeMappingNoLock(typeof(IVectorView<>), typeof(ABI.System.Collections.Generic.IReadOnlyList<>));
+            // The IBindable* types have the same IID on both MUX and WUX, so we can use the same type in both scenarios.
             RegisterCustomTypeToHelperTypeMappingNoLock(typeof(Microsoft.UI.Xaml.Interop.IBindableVector), typeof(ABI.System.Collections.IList));
 
 #if NET
diff --git a/src/WinRT.Runtime/Projections/ICommand.net5.cs b/src/WinRT.Runtime/Projections/ICommand.net5.cs
index 7f7308629..4fe21ab2f 100644
--- a/src/WinRT.Runtime/Projections/ICommand.net5.cs
+++ b/src/WinRT.Runtime/Projections/ICommand.net5.cs
@@ -74,6 +74,7 @@ public static unsafe EventHandlerEventSource Get_CanExecuteChanged2(IObjectRefer
         }
     }
 
+    // ICommand has the same IID for both Windows.UI.Xaml.Input.ICommand and Microsoft.UI.Xaml.Input.ICommand, so we can use one interface definition for both without marking it as a WUX/MUX type.
     [EditorBrowsable(EditorBrowsableState.Never)]
     [Guid("E5AF3542-CA67-4081-995B-709DD13792DF")]
     [DynamicInterfaceCastableImplementation]
diff --git a/src/WinRT.Runtime/Projections/ICustomPropertyProvider.net5.cs b/src/WinRT.Runtime/Projections/ICustomPropertyProvider.net5.cs
index cd63ce463..b982623e9 100644
--- a/src/WinRT.Runtime/Projections/ICustomPropertyProvider.net5.cs
+++ b/src/WinRT.Runtime/Projections/ICustomPropertyProvider.net5.cs
@@ -6,6 +6,8 @@
 using System.Runtime.InteropServices;
 using WinRT;
 
+// These types have the same GUIDs in both Microsoft.UI.Xaml and Windows.UI.Xaml,
+// so we don't need to duplicate them for the internal usage here as they can be transparently used by both WUX and MUX.
 namespace Microsoft.UI.Xaml.Data
 {
     [global::WinRT.WindowsRuntimeType]
diff --git a/src/WinRT.Runtime/Projections/INotifyCollectionChanged.net5.cs b/src/WinRT.Runtime/Projections/INotifyCollectionChanged.net5.cs
index 5370dceba..b812db480 100644
--- a/src/WinRT.Runtime/Projections/INotifyCollectionChanged.net5.cs
+++ b/src/WinRT.Runtime/Projections/INotifyCollectionChanged.net5.cs
@@ -3,8 +3,10 @@
 
 using System;
 using System.ComponentModel;
+using System.Reflection;
 using System.Runtime.InteropServices;
 using WinRT;
+using WinRT.Interop;
 
 namespace ABI.System.Collections.Specialized
 {
@@ -35,7 +37,9 @@ static class INotifyCollectionChangedMethods
             });
         }
 
-        public static global::System.Guid IID => global::WinRT.Interop.IID.IID_INotifyCollectionChanged;
+        public static global::System.Guid IID => FeatureSwitches.UseWindowsUIXamlProjections
+            ? global::WinRT.Interop.IID.IID_WUX_INotifyCollectionChanged
+            : global::WinRT.Interop.IID.IID_MUX_INotifyCollectionChanged;
 
         public static IntPtr AbiToProjectionVftablePtr => INotifyCollectionChanged.Vftbl.AbiToProjectionVftablePtr;
     }
@@ -43,6 +47,7 @@ static class INotifyCollectionChangedMethods
     [DynamicInterfaceCastableImplementation]
     [EditorBrowsable(EditorBrowsableState.Never)]
     [Guid("530155E1-28A5-5693-87CE-30724D95A06D")]
+    [WuxMuxProjectedType]
     internal unsafe interface INotifyCollectionChanged : global::System.Collections.Specialized.INotifyCollectionChanged
     {
         [Guid("530155E1-28A5-5693-87CE-30724D95A06D")]
@@ -121,7 +126,6 @@ private static unsafe int Do_Abi_remove_CollectionChanged_1(IntPtr thisPtr, glob
                 }
             }
         }
-        internal static ObjectReference<Vftbl> FromAbi(IntPtr thisPtr) => ObjectReference<Vftbl>.FromAbi(thisPtr, global::WinRT.Interop.IID.IID_INotifyCollectionChanged);
 
         private static global::ABI.WinRT.Interop.EventSource<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler> _CollectionChanged(IWinRTObject _this)
         {
diff --git a/src/WinRT.Runtime/Projections/INotifyPropertyChanged.net5.cs b/src/WinRT.Runtime/Projections/INotifyPropertyChanged.net5.cs
index ff411bfe5..1b72b7de9 100644
--- a/src/WinRT.Runtime/Projections/INotifyPropertyChanged.net5.cs
+++ b/src/WinRT.Runtime/Projections/INotifyPropertyChanged.net5.cs
@@ -4,20 +4,23 @@
 using System;
 using System.Runtime.InteropServices;
 using WinRT;
+using WinRT.Interop;
 
 namespace ABI.System.ComponentModel
-{
+{
 #if EMBED
     internal
 #else
     public
 #endif
     static class INotifyPropertyChangedMethods
-    {
-        public static global::System.Guid IID => global::WinRT.Interop.IID.IID_INotifyPropertyChanged;
+    {
+        public static global::System.Guid IID => FeatureSwitches.UseWindowsUIXamlProjections
+            ? global::WinRT.Interop.IID.IID_WUX_INotifyPropertyChanged
+            : global::WinRT.Interop.IID.IID_MUX_INotifyPropertyChanged;
+
+        public static IntPtr AbiToProjectionVftablePtr => INotifyPropertyChanged.Vftbl.AbiToProjectionVftablePtr;
 
-        public static IntPtr AbiToProjectionVftablePtr => INotifyPropertyChanged.Vftbl.AbiToProjectionVftablePtr;
-
         private volatile static global::System.Runtime.CompilerServices.ConditionalWeakTable<object, PropertyChangedEventSource> _PropertyChanged;
         private static global::System.Runtime.CompilerServices.ConditionalWeakTable<object, PropertyChangedEventSource> MakePropertyChangedTable()
         {
@@ -25,7 +28,7 @@ static class INotifyPropertyChangedMethods
             return _PropertyChanged;
         }
         private static global::System.Runtime.CompilerServices.ConditionalWeakTable<object, PropertyChangedEventSource> PropertyChanged => _PropertyChanged ?? MakePropertyChangedTable();
-
+
         public static unsafe global::ABI.WinRT.Interop.EventSource<global::System.ComponentModel.PropertyChangedEventHandler> Get_PropertyChanged2(IObjectReference obj, object thisObj)
         {
             return PropertyChanged.GetValue(thisObj, (key) =>
@@ -41,14 +44,16 @@ static class INotifyPropertyChangedMethods
 
     [DynamicInterfaceCastableImplementation]
     [Guid("90B17601-B065-586E-83D9-9ADC3A695284")]
+    [WuxMuxProjectedType]
     internal unsafe interface INotifyPropertyChanged : global::System.ComponentModel.INotifyPropertyChanged
     {
+#pragma warning disable CA2257
         [Guid("90B17601-B065-586E-83D9-9ADC3A695284")]
-        [StructLayout(LayoutKind.Sequential)]
-#pragma warning disable CA2257 // This member is a type (so it cannot be invoked)
-        public struct Vftbl
+        [StructLayout(LayoutKind.Sequential)]
+        public struct Vftbl
 #pragma warning restore CA2257
         {
+
             internal IInspectable.Vftbl IInspectableVftbl;
 
             private delegate* unmanaged<IntPtr, IntPtr, global::WinRT.EventRegistrationToken*, int> _add_PropertyChanged_0;
@@ -119,11 +124,10 @@ private static unsafe int Do_Abi_remove_PropertyChanged_1(IntPtr thisPtr, global
                 }
             }
         }
-        internal static ObjectReference<Vftbl> FromAbi(IntPtr thisPtr) => ObjectReference<Vftbl>.FromAbi(thisPtr, global::WinRT.Interop.IID.IID_INotifyPropertyChanged);
 
         private static global::ABI.WinRT.Interop.EventSource<global::System.ComponentModel.PropertyChangedEventHandler> _PropertyChanged(IWinRTObject _this)
         {
-            var _obj = _this.GetObjectReferenceForType(typeof(global::System.ComponentModel.INotifyPropertyChanged).TypeHandle);
+            var _obj = _this.GetObjectReferenceForType(typeof(global::System.ComponentModel.INotifyPropertyChanged).TypeHandle);
             return INotifyPropertyChangedMethods.Get_PropertyChanged2(_obj, _this);
         }
 
diff --git a/src/WinRT.Runtime/Projections/NotifyCollectionChangedAction.cs b/src/WinRT.Runtime/Projections/NotifyCollectionChangedAction.cs
index b6ccf1bc7..dccf0cc49 100644
--- a/src/WinRT.Runtime/Projections/NotifyCollectionChangedAction.cs
+++ b/src/WinRT.Runtime/Projections/NotifyCollectionChangedAction.cs
@@ -1,10 +1,15 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using WinRT;
+
 namespace ABI.System.Collections.Specialized
 {
     static class NotifyCollectionChangedAction
     {
-        public static string GetGuidSignature() => "enum(Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction;i4)";
+        public static string GetGuidSignature() =>
+            FeatureSwitches.UseWindowsUIXamlProjections
+            ? "enum(Windows.UI.Xaml.Interop.NotifyCollectionChangedAction;i4)"
+            : "enum(Microsoft.UI.Xaml.Interop.NotifyCollectionChangedAction;i4)";
     }
 }
diff --git a/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventArgs.cs b/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventArgs.cs
index 728a81fff..5cb24a1e6 100644
--- a/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventArgs.cs
+++ b/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventArgs.cs
@@ -1,89 +1,96 @@
 // Copyright (c) Microsoft Corporation.
-// Licensed under the MIT License.
-
-using ABI.Microsoft.UI.Xaml.Interop;
-using System;
-using System.ComponentModel;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using WinRT;
-using WinRT.Interop;
-
-namespace ABI.Microsoft.UI.Xaml.Interop
-{
+// Licensed under the MIT License.
+
+using ABI.Microsoft.UI.Xaml.Interop;
+using System;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using WinRT;
+using WinRT.Interop;
+
+namespace ABI.Microsoft.UI.Xaml.Interop
+{
 #if !NET
     [global::WinRT.ObjectReferenceWrapper(nameof(_obj))]
-#endif
-    [Guid("5108EBA4-4892-5A20-8374-A96815E0FD27")]
-    internal sealed unsafe class WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory
-    {
-        private readonly IObjectReference _obj;
-        public IntPtr ThisPtr => _obj.ThisPtr;
-
-        public static readonly WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory Instance = new();
-
-        private WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory()
+#endif
+    [Guid("5108EBA4-4892-5A20-8374-A96815E0FD27")]
+    internal sealed unsafe class WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory
+    {
+        private readonly IObjectReference _obj;
+        public IntPtr ThisPtr => _obj.ThisPtr;
+
+        public static readonly WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory Instance = new();
+
+        private WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory()
+        {
+#if NET
+            _obj = FeatureSwitches.UseWindowsUIXamlProjections
+                ? ActivationFactory.Get("Windows.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", IID.IID_WUX_INotifyCollectionChangedEventArgsFactory)
+                : ActivationFactory.Get("Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", IID.IID_MUX_INotifyCollectionChangedEventArgsFactory);
+#else
+            _obj = ActivationFactory.Get<IUnknownVftbl>("Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", IID.IID_MUX_INotifyCollectionChangedEventArgsFactory);
+#endif
+        }
+
+        public unsafe ObjectReferenceValue CreateInstanceWithAllParameters(global::System.Collections.Specialized.NotifyCollectionChangedAction action, global::System.Collections.IList newItems, global::System.Collections.IList oldItems, int newIndex, int oldIndex)
         {
-#if NET
-            _obj = ActivationFactory.Get("Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", IID.IID_INotifyCollectionChangedEventArgsFactory);
-#else
-            _obj = ActivationFactory.Get<IUnknownVftbl>("Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs", IID.IID_INotifyCollectionChangedEventArgsFactory);
-#endif
-        }
-
-        public unsafe ObjectReferenceValue CreateInstanceWithAllParameters(global::System.Collections.Specialized.NotifyCollectionChangedAction action, global::System.Collections.IList newItems, global::System.Collections.IList oldItems, int newIndex, int oldIndex)
-        {
-            ObjectReferenceValue __newItems = default;
-            ObjectReferenceValue __oldItems = default;
-            IntPtr __innerInterface = default;
-            IntPtr __retval = default;
-            try
+            ObjectReferenceValue __newItems = default;
+            ObjectReferenceValue __oldItems = default;
+            IntPtr __innerInterface = default;
+            IntPtr __retval = default;
+            try
             {
-#if NET
-                __newItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(newItems, global::ABI.System.Collections.IListMethods.IID);
+#if NET
+                __newItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(newItems, global::ABI.System.Collections.IListMethods.IID);
                 __oldItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(oldItems, global::ABI.System.Collections.IListMethods.IID);
-#else
-                __newItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(newItems);
-                __oldItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(oldItems);
-#endif
-                global::WinRT.ExceptionHelpers.ThrowExceptionForHR((*(delegate* unmanaged[Stdcall]<IntPtr, global::System.Collections.Specialized.NotifyCollectionChangedAction, IntPtr, IntPtr, int, int, IntPtr, IntPtr*, IntPtr*, int>**)ThisPtr)[6](
-                    ThisPtr,
-                    action,
-                    MarshalInterface<global::System.Collections.IList>.GetAbi(__newItems),
-                    MarshalInterface<global::System.Collections.IList>.GetAbi(__oldItems),
-                    newIndex,
-                    oldIndex,
-                    IntPtr.Zero,
-                    &__innerInterface,
-                    &__retval));
-                return new ObjectReferenceValue(__retval);
-            }
-            finally
-            {
-                __newItems.Dispose();
-                __oldItems.Dispose();
-                MarshalInspectable<object>.DisposeAbi(__innerInterface);
-            }
-        }
-    }
-}
-
-namespace ABI.System.Collections.Specialized
-{
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    [StructLayout(LayoutKind.Sequential)]
-#if EMBED
-    internal
-#else
-    public
-#endif
-    struct NotifyCollectionChangedEventArgs
+#else
+                __newItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(newItems);
+                __oldItems = MarshalInterface<global::System.Collections.IList>.CreateMarshaler2(oldItems);
+#endif
+                global::WinRT.ExceptionHelpers.ThrowExceptionForHR((*(delegate* unmanaged[Stdcall]<IntPtr, global::System.Collections.Specialized.NotifyCollectionChangedAction, IntPtr, IntPtr, int, int, IntPtr, IntPtr*, IntPtr*, int>**)ThisPtr)[6](
+                    ThisPtr,
+                    action,
+                    MarshalInterface<global::System.Collections.IList>.GetAbi(__newItems),
+                    MarshalInterface<global::System.Collections.IList>.GetAbi(__oldItems),
+                    newIndex,
+                    oldIndex,
+                    IntPtr.Zero,
+                    &__innerInterface,
+                    &__retval));
+                return new ObjectReferenceValue(__retval);
+            }
+            finally
+            {
+                __newItems.Dispose();
+                __oldItems.Dispose();
+                MarshalInspectable<object>.DisposeAbi(__innerInterface);
+            }
+        }
+    }
+}
+
+namespace ABI.System.Collections.Specialized
+{
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    [StructLayout(LayoutKind.Sequential)]
+    [WuxMuxProjectedType]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct NotifyCollectionChangedEventArgs
     {
-        public static IObjectReference CreateMarshaler(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs value)
-        {
-            if (value is null)
-            {
-                return null;
+        private static ref readonly Guid Interface_IID => ref FeatureSwitches.UseWindowsUIXamlProjections
+            ? ref IID.IID_WUX_INotifyCollectionChangedEventArgs
+            : ref IID.IID_MUX_INotifyCollectionChangedEventArgs;
+
+        public static IObjectReference CreateMarshaler(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs value)
+        {
+            if (value is null)
+            {
+                return null;
             }
 
             ObjectReferenceValue _value = default;
@@ -98,26 +105,26 @@ public static IObjectReference CreateMarshaler(global::System.Collections.Specia
             }
         }
 
-        public static ObjectReferenceValue CreateMarshaler2(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs value)
-        {
-            if (value is null)
-            {
-                return new ObjectReferenceValue();
-            }
-
-            return WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory.Instance.CreateInstanceWithAllParameters(value.Action, value.NewItems, value.OldItems, value.NewStartingIndex, value.OldStartingIndex);
-        }
-
-        public static IntPtr GetAbi(IObjectReference m) => m?.ThisPtr ?? IntPtr.Zero;
-
-        public static global::System.Collections.Specialized.NotifyCollectionChangedEventArgs FromAbi(IntPtr ptr)
-        {
-            if (ptr == IntPtr.Zero)
-            {
-                return null;
-            }
-
-            return CreateNotifyCollectionChangedEventArgs(ptr);
+        public static ObjectReferenceValue CreateMarshaler2(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs value)
+        {
+            if (value is null)
+            {
+                return new ObjectReferenceValue();
+            }
+
+            return WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory.Instance.CreateInstanceWithAllParameters(value.Action, value.NewItems, value.OldItems, value.NewStartingIndex, value.OldStartingIndex);
+        }
+
+        public static IntPtr GetAbi(IObjectReference m) => m?.ThisPtr ?? IntPtr.Zero;
+
+        public static global::System.Collections.Specialized.NotifyCollectionChangedEventArgs FromAbi(IntPtr ptr)
+        {
+            if (ptr == IntPtr.Zero)
+            {
+                return null;
+            }
+
+            return CreateNotifyCollectionChangedEventArgs(ptr);
         }
 
         private static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventArgs CreateNotifyCollectionChangedEventArgs(IntPtr ptr)
@@ -132,7 +139,7 @@ public static ObjectReferenceValue CreateMarshaler2(global::System.Collections.S
             try
             {
                 // Call can come from CreateObject which means it might not be on the right interface.
-                global::WinRT.ExceptionHelpers.ThrowExceptionForHR(Marshal.QueryInterface(ptr, ref Unsafe.AsRef(in IID.IID_INotifyCollectionChangedEventArgs), out thisPtr));
+                global::WinRT.ExceptionHelpers.ThrowExceptionForHR(Marshal.QueryInterface(ptr, ref Unsafe.AsRef(in Interface_IID), out thisPtr));
 
                 global::WinRT.ExceptionHelpers.ThrowExceptionForHR((*(delegate* unmanaged[Stdcall]<IntPtr, global::System.Collections.Specialized.NotifyCollectionChangedAction*, int>**)thisPtr)[6](thisPtr, &action));
                 global::WinRT.ExceptionHelpers.ThrowExceptionForHR((*(delegate* unmanaged[Stdcall]<IntPtr, IntPtr*, int>**)thisPtr)[7](thisPtr, &newItems));
@@ -152,52 +159,56 @@ public static ObjectReferenceValue CreateMarshaler2(global::System.Collections.S
                 MarshalInterface<global::System.Collections.IList>.DisposeAbi(oldItems);
                 Marshal.Release(thisPtr);
             }
-        }
-
-        private static global::System.Collections.Specialized.NotifyCollectionChangedEventArgs CreateNotifyCollectionChangedEventArgs(
-            global::System.Collections.Specialized.NotifyCollectionChangedAction action,
-            global::System.Collections.IList newItems,
-            global::System.Collections.IList oldItems,
-            int newStartingIndex,
-            int oldStartingIndex) =>
-            action switch
-            {
-                global::System.Collections.Specialized.NotifyCollectionChangedAction.Add => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, newItems, newStartingIndex),
-                global::System.Collections.Specialized.NotifyCollectionChangedAction.Remove => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, oldItems, oldStartingIndex),
-                global::System.Collections.Specialized.NotifyCollectionChangedAction.Replace => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, newItems, oldItems, newStartingIndex),
-                global::System.Collections.Specialized.NotifyCollectionChangedAction.Move => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, newItems, newStartingIndex, oldStartingIndex),
-                global::System.Collections.Specialized.NotifyCollectionChangedAction.Reset => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(global::System.Collections.Specialized.NotifyCollectionChangedAction.Reset),
-                _ => throw new ArgumentException(),
-            };
-
-        public static unsafe void CopyManaged(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs o, IntPtr dest)
-        {
-            *(IntPtr*)dest.ToPointer() = CreateMarshaler2(o).Detach();
-        }
-
-        public static IntPtr FromManaged(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs value)
-        {
-            if (value is null)
-            {
-                return IntPtr.Zero;
-            }
-            return CreateMarshaler2(value).Detach();
-        }
-
-        public static void DisposeMarshaler(IObjectReference m) { m?.Dispose(); }
+        }
+
+        private static global::System.Collections.Specialized.NotifyCollectionChangedEventArgs CreateNotifyCollectionChangedEventArgs(
+            global::System.Collections.Specialized.NotifyCollectionChangedAction action,
+            global::System.Collections.IList newItems,
+            global::System.Collections.IList oldItems,
+            int newStartingIndex,
+            int oldStartingIndex) =>
+            action switch
+            {
+                global::System.Collections.Specialized.NotifyCollectionChangedAction.Add => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, newItems, newStartingIndex),
+                global::System.Collections.Specialized.NotifyCollectionChangedAction.Remove => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, oldItems, oldStartingIndex),
+                global::System.Collections.Specialized.NotifyCollectionChangedAction.Replace => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, newItems, oldItems, newStartingIndex),
+                global::System.Collections.Specialized.NotifyCollectionChangedAction.Move => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(action, newItems, newStartingIndex, oldStartingIndex),
+                global::System.Collections.Specialized.NotifyCollectionChangedAction.Reset => new global::System.Collections.Specialized.NotifyCollectionChangedEventArgs(global::System.Collections.Specialized.NotifyCollectionChangedAction.Reset),
+                _ => throw new ArgumentException(),
+            };
+
+        public static unsafe void CopyManaged(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs o, IntPtr dest)
+        {
+            *(IntPtr*)dest.ToPointer() = CreateMarshaler2(o).Detach();
+        }
+
+        public static IntPtr FromManaged(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs value)
+        {
+            if (value is null)
+            {
+                return IntPtr.Zero;
+            }
+            return CreateMarshaler2(value).Detach();
+        }
+
+        public static void DisposeMarshaler(IObjectReference m) { m?.Dispose(); }
         public static void DisposeAbi(IntPtr abi) { MarshalInspectable<object>.DisposeAbi(abi); }
 
-        public static unsafe MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.MarshalerArray CreateMarshalerArray(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.CreateMarshalerArray2(array, CreateMarshaler2);
-        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.GetAbiArray(box);
-        public static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.FromAbiArray(box, FromAbi);
-        public static void CopyAbiArray(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] array, object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.CopyAbiArray(array, box, FromAbi);
-        public static (int length, IntPtr data) FromManagedArray(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.FromManagedArray(array, FromManaged);
-        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.MarshalerArray array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.DisposeMarshalerArray(array);
-        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
-
-        public static string GetGuidSignature()
-        {
-            return "rc(Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs;{4cf68d33-e3f2-4964-b85e-945b4f7e2f21})";
-        }
-    }
-}
+        public static unsafe MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.MarshalerArray CreateMarshalerArray(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.CreateMarshalerArray2(array, CreateMarshaler2);
+        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.GetAbiArray(box);
+        public static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.FromAbiArray(box, FromAbi);
+        public static void CopyAbiArray(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] array, object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.CopyAbiArray(array, box, FromAbi);
+        public static (int length, IntPtr data) FromManagedArray(global::System.Collections.Specialized.NotifyCollectionChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.FromManagedArray(array, FromManaged);
+        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.MarshalerArray array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventArgs>.DisposeMarshalerArray(array);
+        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
+
+        public static string GetGuidSignature()
+        {
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                return "rc(Windows.UI.Xaml.Interop.NotifyCollectionChangedEventArgs;{4cf68d33-e3f2-4964-b85e-945b4f7e2f21})";
+            }
+            return "rc(Microsoft.UI.Xaml.Interop.NotifyCollectionChangedEventArgs;{4cf68d33-e3f2-4964-b85e-945b4f7e2f21})";
+        }
+    }
+}
diff --git a/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventHandler.cs b/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventHandler.cs
index 05a433e46..18333338d 100644
--- a/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventHandler.cs
+++ b/src/WinRT.Runtime/Projections/NotifyCollectionChangedEventHandler.cs
@@ -1,202 +1,205 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT License.
-
-using System;
-using System.Collections.Concurrent;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using WinRT;
-using WinRT.Interop;
-
-namespace ABI.System.Collections.Specialized
-{
-
-    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
-    [Guid("8B0909DC-2005-5D93-BF8A-725F017BAA8D")]
-#if EMBED
-    internal
-#else
-    public
-#endif
-    static class NotifyCollectionChangedEventHandler
-    {
-#if !NET
-        private unsafe delegate int Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e);
-#endif
-
-        private static readonly global::WinRT.Interop.IDelegateVftbl AbiToProjectionVftable;
-        public static readonly IntPtr AbiToProjectionVftablePtr;
-
-        static unsafe NotifyCollectionChangedEventHandler()
-        {
-            AbiToProjectionVftable = new global::WinRT.Interop.IDelegateVftbl
-            {
-                IUnknownVftbl = global::WinRT.Interop.IUnknownVftbl.AbiToProjectionVftbl,
-#if !NET
-                Invoke = Marshal.GetFunctionPointerForDelegate(AbiInvokeDelegate = (Abi_Invoke)Do_Abi_Invoke)
-#else
-                Invoke = (IntPtr)(delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)&Do_Abi_Invoke
-#endif
-            };
-            var nativeVftbl = ComWrappersSupport.AllocateVtableMemory(typeof(NotifyCollectionChangedEventHandler), sizeof(global::WinRT.Interop.IDelegateVftbl));
-            *(global::WinRT.Interop.IDelegateVftbl*)nativeVftbl = AbiToProjectionVftable;
-            AbiToProjectionVftablePtr = nativeVftbl;
-            ComWrappersSupport.RegisterDelegateFactory(typeof(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler), CreateRcw);
-        }
-
-        public static global::System.Delegate AbiInvokeDelegate { get; }
-
-        public static Guid IID => global::WinRT.Interop.IID.IID_NotifyCollectionChangedEventHandler;
-
-        public static unsafe IObjectReference CreateMarshaler(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler managedDelegate) =>
-            managedDelegate is null ? null : MarshalDelegate.CreateMarshaler(managedDelegate, IID);
-
-        public static unsafe ObjectReferenceValue CreateMarshaler2(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler managedDelegate) => 
-            MarshalDelegate.CreateMarshaler2(managedDelegate, IID);
-
-        public static IntPtr GetAbi(IObjectReference value) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.GetAbi(value);
-
-        public static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventHandler FromAbi(IntPtr nativeDelegate)
-        {
-            return MarshalDelegate.FromAbi<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>(nativeDelegate);
-        }
-
-        public static global::System.Collections.Specialized.NotifyCollectionChangedEventHandler CreateRcw(IntPtr ptr)
-        {
-            return new global::System.Collections.Specialized.NotifyCollectionChangedEventHandler(new NativeDelegateWrapper(ComWrappersSupport.GetObjectReferenceForInterface<IDelegateVftbl>(ptr, IID)).Invoke);
-        }
-
-#if !NET
-        [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
-        private sealed class NativeDelegateWrapper
-#else
-        private sealed class NativeDelegateWrapper : IWinRTObject
-#endif
-        {
-            private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;
-
-            public NativeDelegateWrapper(ObjectReference<global::WinRT.Interop.IDelegateVftbl> nativeDelegate)
-            {
-                _nativeDelegate = nativeDelegate;
-            }
-
-#if NET
-            IObjectReference IWinRTObject.NativeObject => _nativeDelegate;
-            bool IWinRTObject.HasUnwrappableNativeObject => true;
-            private volatile ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> _queryInterfaceCache;
-            private ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> MakeQueryInterfaceCache()
-            {
-                global::System.Threading.Interlocked.CompareExchange(ref _queryInterfaceCache, new ConcurrentDictionary<RuntimeTypeHandle, IObjectReference>(), null);
-                return _queryInterfaceCache;
-            }
-            ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> IWinRTObject.QueryInterfaceCache => _queryInterfaceCache ?? MakeQueryInterfaceCache();
-
-            private volatile ConcurrentDictionary<RuntimeTypeHandle, object> _additionalTypeData;
-            private ConcurrentDictionary<RuntimeTypeHandle, object> MakeAdditionalTypeData()
-            {
-                global::System.Threading.Interlocked.CompareExchange(ref _additionalTypeData, new ConcurrentDictionary<RuntimeTypeHandle, object>(), null);
-                return _additionalTypeData;
-            }
-            ConcurrentDictionary<RuntimeTypeHandle, object> IWinRTObject.AdditionalTypeData => _additionalTypeData ?? MakeAdditionalTypeData();
-#endif
-
-            public unsafe void Invoke(object sender, global::System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
-            {
-                IntPtr ThisPtr = _nativeDelegate.ThisPtr;
-#if !NET
-                var abiInvoke = Marshal.GetDelegateForFunctionPointer<Abi_Invoke>(_nativeDelegate.Vftbl.Invoke);
-#else
-                var abiInvoke = (delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)(_nativeDelegate.Vftbl.Invoke);
-#endif
-                ObjectReferenceValue __sender = default;
-                ObjectReferenceValue __e = default;
-                try
-                {
-                    __sender = MarshalInspectable<object>.CreateMarshaler2(sender);
-                    __e = global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.CreateMarshaler2(e);
-                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(abiInvoke(ThisPtr, MarshalInspectable<object>.GetAbi(__sender), MarshalInspectable<object>.GetAbi(__e)));
-                }
-                finally
-                {
-                    MarshalInspectable<object>.DisposeMarshaler(__sender);
-                    MarshalInspectable<object>.DisposeMarshaler(__e);
-                }
-
-            }
-        }
-
-        public static IntPtr FromManaged(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler managedDelegate) => 
-            CreateMarshaler2(managedDelegate).Detach();
-
-        public static void DisposeMarshaler(IObjectReference value) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.DisposeMarshaler(value);
-
-        public static void DisposeAbi(IntPtr abi) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.DisposeAbi(abi);
-
-        public static unsafe MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.MarshalerArray CreateMarshalerArray(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.CreateMarshalerArray2(array, CreateMarshaler2);
-        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.GetAbiArray(box);
-        public static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.FromAbiArray(box, FromAbi);
-        public static void CopyAbiArray(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] array, object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.CopyAbiArray(array, box, FromAbi);
-        public static (int length, IntPtr data) FromManagedArray(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.FromManagedArray(array, FromManaged);
-        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.MarshalerArray array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.DisposeMarshalerArray(array);
-        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
-
-#if NET
-        [UnmanagedCallersOnly(CallConvs = new[] { typeof(CallConvStdcall) })]
-#endif
-        private static unsafe int Do_Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e)
-        {
-            try
-            {
-#if NET
-                var invoke = ComWrappersSupport.FindObject<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>(thisPtr);
-                invoke.Invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.FromAbi(e));
-#else
-                global::WinRT.ComWrappersSupport.MarshalDelegateInvoke(thisPtr, (global::System.Collections.Specialized.NotifyCollectionChangedEventHandler invoke) =>
-                {
-                    invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.FromAbi(e));
-                });
-#endif
-            }
-            catch (global::System.Exception __exception__)
-            {
-                global::WinRT.ExceptionHelpers.SetErrorInfo(__exception__);
-                return global::WinRT.ExceptionHelpers.GetHRForException(__exception__);
-            }
-            return 0;
-        }
-    }
-
-    internal sealed unsafe class NotifyCollectionChangedEventHandlerEventSource : global::ABI.WinRT.Interop.EventSource<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>
-    {
-        internal NotifyCollectionChangedEventHandlerEventSource(
-            IObjectReference objectReference,
-#if NET
-            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, EventRegistrationToken*, int> addHandler,
-#else
-            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, out EventRegistrationToken, int> addHandler,
-#endif
-            delegate* unmanaged[Stdcall]<IntPtr, EventRegistrationToken, int> removeHandler)
-            : base(objectReference, addHandler, removeHandler)
-        {
-        }
-
-        protected override ObjectReferenceValue CreateMarshaler(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler del) =>
-            NotifyCollectionChangedEventHandler.CreateMarshaler2(del);
-
-        protected override global::ABI.WinRT.Interop.EventSourceState<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler> CreateEventSourceState() =>
-            new EventState(ObjectReference.ThisPtr, Index);
-
-        private sealed class EventState : global::ABI.WinRT.Interop.EventSourceState<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>
-        {
-            public EventState(IntPtr obj, int index)
-                : base(obj, index)
-            {
-            }
-
-            protected override global::System.Collections.Specialized.NotifyCollectionChangedEventHandler GetEventInvoke()
-            {
-                return (obj, e) => targetDelegate?.Invoke(obj, e);
-            }
-        }
-    }
-}
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Concurrent;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using WinRT;
+using WinRT.Interop;
+
+namespace ABI.System.Collections.Specialized
+{
+
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    [Guid("8B0909DC-2005-5D93-BF8A-725F017BAA8D")]
+    [WuxMuxProjectedType]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class NotifyCollectionChangedEventHandler
+    {
+#if !NET
+        private unsafe delegate int Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e);
+#endif
+
+        private static readonly global::WinRT.Interop.IDelegateVftbl AbiToProjectionVftable;
+        public static readonly IntPtr AbiToProjectionVftablePtr;
+
+        static unsafe NotifyCollectionChangedEventHandler()
+        {
+            AbiToProjectionVftable = new global::WinRT.Interop.IDelegateVftbl
+            {
+                IUnknownVftbl = global::WinRT.Interop.IUnknownVftbl.AbiToProjectionVftbl,
+#if !NET
+                Invoke = Marshal.GetFunctionPointerForDelegate(AbiInvokeDelegate = (Abi_Invoke)Do_Abi_Invoke)
+#else
+                Invoke = (IntPtr)(delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)&Do_Abi_Invoke
+#endif
+            };
+            var nativeVftbl = ComWrappersSupport.AllocateVtableMemory(typeof(NotifyCollectionChangedEventHandler), sizeof(global::WinRT.Interop.IDelegateVftbl));
+            *(global::WinRT.Interop.IDelegateVftbl*)nativeVftbl = AbiToProjectionVftable;
+            AbiToProjectionVftablePtr = nativeVftbl;
+            ComWrappersSupport.RegisterDelegateFactory(typeof(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler), CreateRcw);
+        }
+
+        public static global::System.Delegate AbiInvokeDelegate { get; }
+
+        public static Guid IID => FeatureSwitches.UseWindowsUIXamlProjections
+            ? global::WinRT.Interop.IID.IID_WUX_NotifyCollectionChangedEventHandler
+            : global::WinRT.Interop.IID.IID_MUX_NotifyCollectionChangedEventHandler;
+
+        public static unsafe IObjectReference CreateMarshaler(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler managedDelegate) =>
+            managedDelegate is null ? null : MarshalDelegate.CreateMarshaler(managedDelegate, IID);
+
+        public static unsafe ObjectReferenceValue CreateMarshaler2(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler managedDelegate) => 
+            MarshalDelegate.CreateMarshaler2(managedDelegate, IID);
+
+        public static IntPtr GetAbi(IObjectReference value) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.GetAbi(value);
+
+        public static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventHandler FromAbi(IntPtr nativeDelegate)
+        {
+            return MarshalDelegate.FromAbi<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>(nativeDelegate);
+        }
+
+        public static global::System.Collections.Specialized.NotifyCollectionChangedEventHandler CreateRcw(IntPtr ptr)
+        {
+            return new global::System.Collections.Specialized.NotifyCollectionChangedEventHandler(new NativeDelegateWrapper(ComWrappersSupport.GetObjectReferenceForInterface<IDelegateVftbl>(ptr, IID)).Invoke);
+        }
+
+#if !NET
+        [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
+        private sealed class NativeDelegateWrapper
+#else
+        private sealed class NativeDelegateWrapper : IWinRTObject
+#endif
+        {
+            private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;
+
+            public NativeDelegateWrapper(ObjectReference<global::WinRT.Interop.IDelegateVftbl> nativeDelegate)
+            {
+                _nativeDelegate = nativeDelegate;
+            }
+
+#if NET
+            IObjectReference IWinRTObject.NativeObject => _nativeDelegate;
+            bool IWinRTObject.HasUnwrappableNativeObject => true;
+            private volatile ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> _queryInterfaceCache;
+            private ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> MakeQueryInterfaceCache()
+            {
+                global::System.Threading.Interlocked.CompareExchange(ref _queryInterfaceCache, new ConcurrentDictionary<RuntimeTypeHandle, IObjectReference>(), null);
+                return _queryInterfaceCache;
+            }
+            ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> IWinRTObject.QueryInterfaceCache => _queryInterfaceCache ?? MakeQueryInterfaceCache();
+
+            private volatile ConcurrentDictionary<RuntimeTypeHandle, object> _additionalTypeData;
+            private ConcurrentDictionary<RuntimeTypeHandle, object> MakeAdditionalTypeData()
+            {
+                global::System.Threading.Interlocked.CompareExchange(ref _additionalTypeData, new ConcurrentDictionary<RuntimeTypeHandle, object>(), null);
+                return _additionalTypeData;
+            }
+            ConcurrentDictionary<RuntimeTypeHandle, object> IWinRTObject.AdditionalTypeData => _additionalTypeData ?? MakeAdditionalTypeData();
+#endif
+
+            public unsafe void Invoke(object sender, global::System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+            {
+                IntPtr ThisPtr = _nativeDelegate.ThisPtr;
+#if !NET
+                var abiInvoke = Marshal.GetDelegateForFunctionPointer<Abi_Invoke>(_nativeDelegate.Vftbl.Invoke);
+#else
+                var abiInvoke = (delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)(_nativeDelegate.Vftbl.Invoke);
+#endif
+                ObjectReferenceValue __sender = default;
+                ObjectReferenceValue __e = default;
+                try
+                {
+                    __sender = MarshalInspectable<object>.CreateMarshaler2(sender);
+                    __e = global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.CreateMarshaler2(e);
+                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(abiInvoke(ThisPtr, MarshalInspectable<object>.GetAbi(__sender), MarshalInspectable<object>.GetAbi(__e)));
+                }
+                finally
+                {
+                    MarshalInspectable<object>.DisposeMarshaler(__sender);
+                    MarshalInspectable<object>.DisposeMarshaler(__e);
+                }
+
+            }
+        }
+
+        public static IntPtr FromManaged(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler managedDelegate) => 
+            CreateMarshaler2(managedDelegate).Detach();
+
+        public static void DisposeMarshaler(IObjectReference value) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.DisposeMarshaler(value);
+
+        public static void DisposeAbi(IntPtr abi) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.DisposeAbi(abi);
+
+        public static unsafe MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.MarshalerArray CreateMarshalerArray(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.CreateMarshalerArray2(array, CreateMarshaler2);
+        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.GetAbiArray(box);
+        public static unsafe global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.FromAbiArray(box, FromAbi);
+        public static void CopyAbiArray(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] array, object box) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.CopyAbiArray(array, box, FromAbi);
+        public static (int length, IntPtr data) FromManagedArray(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.FromManagedArray(array, FromManaged);
+        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.MarshalerArray array) => MarshalInterfaceHelper<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>.DisposeMarshalerArray(array);
+        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
+
+#if NET
+        [UnmanagedCallersOnly(CallConvs = new[] { typeof(CallConvStdcall) })]
+#endif
+        private static unsafe int Do_Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e)
+        {
+            try
+            {
+#if NET
+                var invoke = ComWrappersSupport.FindObject<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>(thisPtr);
+                invoke.Invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.FromAbi(e));
+#else
+                global::WinRT.ComWrappersSupport.MarshalDelegateInvoke(thisPtr, (global::System.Collections.Specialized.NotifyCollectionChangedEventHandler invoke) =>
+                {
+                    invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.FromAbi(e));
+                });
+#endif
+            }
+            catch (global::System.Exception __exception__)
+            {
+                global::WinRT.ExceptionHelpers.SetErrorInfo(__exception__);
+                return global::WinRT.ExceptionHelpers.GetHRForException(__exception__);
+            }
+            return 0;
+        }
+    }
+
+    internal sealed unsafe class NotifyCollectionChangedEventHandlerEventSource : global::ABI.WinRT.Interop.EventSource<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>
+    {
+        internal NotifyCollectionChangedEventHandlerEventSource(
+            IObjectReference objectReference,
+#if NET
+            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, EventRegistrationToken*, int> addHandler,
+#else
+            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, out EventRegistrationToken, int> addHandler,
+#endif
+            delegate* unmanaged[Stdcall]<IntPtr, EventRegistrationToken, int> removeHandler)
+            : base(objectReference, addHandler, removeHandler)
+        {
+        }
+
+        protected override ObjectReferenceValue CreateMarshaler(global::System.Collections.Specialized.NotifyCollectionChangedEventHandler del) =>
+            NotifyCollectionChangedEventHandler.CreateMarshaler2(del);
+
+        protected override global::ABI.WinRT.Interop.EventSourceState<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler> CreateEventSourceState() =>
+            new EventState(ObjectReference.ThisPtr, Index);
+
+        private sealed class EventState : global::ABI.WinRT.Interop.EventSourceState<global::System.Collections.Specialized.NotifyCollectionChangedEventHandler>
+        {
+            public EventState(IntPtr obj, int index)
+                : base(obj, index)
+            {
+            }
+
+            protected override global::System.Collections.Specialized.NotifyCollectionChangedEventHandler GetEventInvoke()
+            {
+                return (obj, e) => targetDelegate?.Invoke(obj, e);
+            }
+        }
+    }
+}
diff --git a/src/WinRT.Runtime/Projections/PropertyChangedEventArgs.cs b/src/WinRT.Runtime/Projections/PropertyChangedEventArgs.cs
index 5273edb40..61116de9d 100644
--- a/src/WinRT.Runtime/Projections/PropertyChangedEventArgs.cs
+++ b/src/WinRT.Runtime/Projections/PropertyChangedEventArgs.cs
@@ -1,175 +1,177 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT License.
-
-using System;
-using System.ComponentModel;
-using System.Runtime.InteropServices;
-using WinRT;
-using WinRT.Interop;
-
-namespace ABI.Microsoft.UI.Xaml.Data
-{
-    [Guid("63D0C952-396B-54F4-AF8C-BA8724A427BF")]
-    [StructLayout(LayoutKind.Sequential)]
-    internal unsafe struct IPropertyChangedEventArgsVftbl
-    {
-        internal IInspectable.Vftbl IInspectableVftbl;
-        private void* _get_PropertyName_0;
-        public delegate* unmanaged[Stdcall]<IntPtr, IntPtr*, int> get_PropertyName_0 => (delegate* unmanaged[Stdcall]<IntPtr, IntPtr*, int>)_get_PropertyName_0;
-    }
-
-#if !NET
-    [global::WinRT.ObjectReferenceWrapper(nameof(_obj))]
-#endif
-    [Guid("7C0C27A8-0B41-5070-B160-FC9AE960A36C")]
-    internal sealed unsafe class WinRTPropertyChangedEventArgsRuntimeClassFactory
-    {
-        [Guid("7C0C27A8-0B41-5070-B160-FC9AE960A36C")]
-        [StructLayout(LayoutKind.Sequential)]
-        public struct Vftbl
-        {
-            internal IInspectable.Vftbl IInspectableVftbl;
-            private void* _CreateInstance_0;
-            public delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, IntPtr*, IntPtr*, int> CreateInstance_0 => (delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, IntPtr*, IntPtr*, int>)_CreateInstance_0;
-        }
-        public static ObjectReference<Vftbl> FromAbi(IntPtr thisPtr) => ObjectReference<Vftbl>.FromAbi(thisPtr, global::WinRT.Interop.IID.IID_PropertyChangedEventArgsRuntimeClassFactory);
-
-        private readonly ObjectReference<Vftbl> _obj;
-        public IntPtr ThisPtr => _obj.ThisPtr;
-        public WinRTPropertyChangedEventArgsRuntimeClassFactory(IObjectReference obj) : this(obj.As<Vftbl>(IID.IID_PropertyChangedEventArgsRuntimeClassFactory)) { }
-        public WinRTPropertyChangedEventArgsRuntimeClassFactory(ObjectReference<Vftbl> obj)
-        {
-            _obj = obj;
-        }
-
-        public unsafe IObjectReference CreateInstance(string name, object baseInterface, out IObjectReference innerInterface)
-        {
-            IObjectReference __baseInterface = default;
-            IntPtr __innerInterface = default;
-            IntPtr __retval = default;
-            try
-            {
-                MarshalString.Pinnable __name = new(name);
-                fixed (void* ___name = __name)
-                {
-                    __baseInterface = MarshalInspectable<object>.CreateMarshaler(baseInterface);
-                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(_obj.Vftbl.CreateInstance_0(ThisPtr, MarshalString.GetAbi(ref __name), MarshalInspectable<object>.GetAbi(__baseInterface), &__innerInterface, &__retval));
-                    innerInterface = ObjectReference<IUnknownVftbl>.FromAbi(__innerInterface, IID.IID_IUnknown);
-                    return ObjectReference<IUnknownVftbl>.Attach(ref __retval, IID.IID_IUnknown);
-                }
-            }
-            finally
-            {
-                MarshalInspectable<object>.DisposeMarshaler(__baseInterface);
-                MarshalInspectable<object>.DisposeAbi(__innerInterface);
-                MarshalInspectable<object>.DisposeAbi(__retval);
-            }
-        }
-
-        public unsafe ObjectReferenceValue CreateInstance(string name)
-        {
-            IntPtr __innerInterface = default;
-            IntPtr __retval = default;
-            try
-            {
-                MarshalString.Pinnable __name = new(name);
-                fixed (void* ___name = __name)
-                {
-                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(_obj.Vftbl.CreateInstance_0(ThisPtr, MarshalString.GetAbi(ref __name), IntPtr.Zero, &__innerInterface, &__retval));
-                    return new ObjectReferenceValue(__retval);
-                }
-            }
-            finally
-            {
-                MarshalInspectable<object>.DisposeAbi(__innerInterface);
-            }
-        }
-
-    }
-}
-
-namespace ABI.System.ComponentModel
-{
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    [StructLayout(LayoutKind.Sequential)]
-#if EMBED
-    internal
-#else
-    public
-#endif
-    unsafe struct PropertyChangedEventArgs
-    {
-        private static readonly ABI.Microsoft.UI.Xaml.Data.WinRTPropertyChangedEventArgsRuntimeClassFactory Instance = new(ActivationFactory.Get("Microsoft.UI.Xaml.Data.PropertyChangedEventArgs"));
-
-        public static IObjectReference CreateMarshaler(global::System.ComponentModel.PropertyChangedEventArgs value)
-        {
-            if (value is null)
-            {
-                return null;
-            }
-
-            return Instance.CreateInstance(value.PropertyName, null, out _);
-        }
-
-        public static ObjectReferenceValue CreateMarshaler2(global::System.ComponentModel.PropertyChangedEventArgs value)
-        {
-            if (value is null)
-            {
-                return new ObjectReferenceValue();
-            }
-
-            return Instance.CreateInstance(value.PropertyName);
-        }
-
-        public static IntPtr GetAbi(IObjectReference m) => m?.ThisPtr ?? IntPtr.Zero;
-
-        public static global::System.ComponentModel.PropertyChangedEventArgs FromAbi(IntPtr ptr)
-        {
-            if (ptr == IntPtr.Zero)
-            {
-                return null;
-            }
-
-            IntPtr propertyName = IntPtr.Zero;
-            try
-            {
-                ExceptionHelpers.ThrowExceptionForHR((**(ABI.Microsoft.UI.Xaml.Data.IPropertyChangedEventArgsVftbl**)ptr).get_PropertyName_0(ptr, &propertyName));
-                return new global::System.ComponentModel.PropertyChangedEventArgs(MarshalString.FromAbi(propertyName));
-            }
-            finally
-            {
-                MarshalString.DisposeAbi(propertyName);
-            }
-        }
-
-        public static unsafe void CopyManaged(global::System.ComponentModel.PropertyChangedEventArgs o, IntPtr dest)
-        {
-            *(IntPtr*)dest.ToPointer() = CreateMarshaler2(o).Detach();
-        }
-
-        public static IntPtr FromManaged(global::System.ComponentModel.PropertyChangedEventArgs value)
-        {
-            if (value is null)
-            {
-                return IntPtr.Zero;
-            }
-            return CreateMarshaler2(value).Detach();
-        }
-
-        public static void DisposeMarshaler(IObjectReference m) { m?.Dispose(); }
-        public static void DisposeAbi(IntPtr abi) { MarshalInspectable<object>.DisposeAbi(abi); }
-
-        public static unsafe MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.MarshalerArray CreateMarshalerArray(global::System.ComponentModel.PropertyChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.CreateMarshalerArray2(array, CreateMarshaler2);
-        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.GetAbiArray(box);
-        public static unsafe global::System.ComponentModel.PropertyChangedEventArgs[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.FromAbiArray(box, FromAbi);
-        public static void CopyAbiArray(global::System.ComponentModel.PropertyChangedEventArgs[] array, object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.CopyAbiArray(array, box, FromAbi);
-        public static (int length, IntPtr data) FromManagedArray(global::System.ComponentModel.PropertyChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.FromManagedArray(array, FromManaged);
-        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.MarshalerArray array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.DisposeMarshalerArray(array);
-        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
-
-        public static string GetGuidSignature()
-        {
-            return "rc(Microsoft.UI.Xaml.Data.NotifyPropertyChangedEventArgs;{4f33a9a0-5cf4-47a4-b16f-d7faaf17457e})";
-        }
-    }
-}
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.ComponentModel;
+using System.Runtime.InteropServices;
+using WinRT;
+using WinRT.Interop;
+
+namespace ABI.Microsoft.UI.Xaml.Data
+{
+    internal sealed unsafe class PropertyChangedEventArgsRuntimeClassFactory
+    {
+        private readonly IObjectReference _obj;
+
+        public PropertyChangedEventArgsRuntimeClassFactory()
+        {
+#if NET
+            _obj = FeatureSwitches.UseWindowsUIXamlProjections
+                ? ActivationFactory.Get("Windows.UI.Xaml.Data.PropertyChangedEventArgs", IID.IID_WUX_PropertyChangedEventArgsRuntimeClassFactory)
+                : ActivationFactory.Get("Microsoft.UI.Xaml.Data.PropertyChangedEventArgs", IID.IID_MUX_PropertyChangedEventArgsRuntimeClassFactory);
+#else
+            _obj = ActivationFactory.Get<IUnknownVftbl>("Microsoft.UI.Xaml.Data.PropertyChangedEventArgs", IID.IID_MUX_PropertyChangedEventArgsRuntimeClassFactory);
+#endif
+        }
+
+        public IObjectReference CreateInstance(string name, object baseInterface, out IObjectReference innerInterface)
+        {
+            IObjectReference __baseInterface = default;
+            IntPtr __innerInterface = default;
+            IntPtr __retval = default;
+            try
+            {
+                MarshalString.Pinnable __name = new(name);
+                fixed (void* ___name = __name)
+                {
+                    __baseInterface = MarshalInspectable<object>.CreateMarshaler(baseInterface);
+                    IntPtr thisPtr = _obj.ThisPtr;
+                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(
+                        ((delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, IntPtr*, IntPtr*, int>)(*(void***)thisPtr)[6])(
+                            thisPtr,
+                            MarshalString.GetAbi(ref __name),
+                            MarshalInspectable<object>.GetAbi(__baseInterface),
+                            &__innerInterface,
+                            &__retval));
+                    innerInterface = ObjectReference<IUnknownVftbl>.FromAbi(__innerInterface, IID.IID_IUnknown);
+                    return ObjectReference<IUnknownVftbl>.Attach(ref __retval, IID.IID_IUnknown);
+                }
+            }
+            finally
+            {
+                MarshalInspectable<object>.DisposeMarshaler(__baseInterface);
+                MarshalInspectable<object>.DisposeAbi(__innerInterface);
+                MarshalInspectable<object>.DisposeAbi(__retval);
+            }
+        }
+
+        public ObjectReferenceValue CreateInstance(string name)
+        {
+            IntPtr __innerInterface = default;
+            IntPtr __retval = default;
+            try
+            {
+                MarshalString.Pinnable __name = new(name);
+                fixed (void* ___name = __name)
+                {
+                    IntPtr thisPtr = _obj.ThisPtr;
+                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(
+                        ((delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, IntPtr*, IntPtr*, int>)(*(void***)thisPtr)[6])(
+                            thisPtr,
+                            MarshalString.GetAbi(ref __name),
+                            IntPtr.Zero,
+                            &__innerInterface,
+                            &__retval));
+                    return new ObjectReferenceValue(__retval);
+                }
+            }
+            finally
+            {
+                MarshalInspectable<object>.DisposeAbi(__innerInterface);
+            }
+        }
+    }
+}
+
+namespace ABI.System.ComponentModel
+{
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    unsafe struct PropertyChangedEventArgs
+    {
+        private static readonly ABI.Microsoft.UI.Xaml.Data.PropertyChangedEventArgsRuntimeClassFactory Instance = new();
+
+        public static IObjectReference CreateMarshaler(global::System.ComponentModel.PropertyChangedEventArgs value)
+        {
+            if (value is null)
+            {
+                return null;
+            }
+
+            return Instance.CreateInstance(value.PropertyName, null, out _);
+        }
+
+        public static ObjectReferenceValue CreateMarshaler2(global::System.ComponentModel.PropertyChangedEventArgs value)
+        {
+            if (value is null)
+            {
+                return new ObjectReferenceValue();
+            }
+
+            return Instance.CreateInstance(value.PropertyName);
+        }
+
+        public static IntPtr GetAbi(IObjectReference m) => m?.ThisPtr ?? IntPtr.Zero;
+
+        public static global::System.ComponentModel.PropertyChangedEventArgs FromAbi(IntPtr ptr)
+        {
+            if (ptr == IntPtr.Zero)
+            {
+                return null;
+            }
+
+            IntPtr propertyName = IntPtr.Zero;
+            try
+            {
+                // We can use the Microsoft.UI.Xaml.Data.IPropertyChangedEventArgsVftbl here in both WUX and MUX because the vtables are laid out the same and we know
+                // that we have either a MUX or WUX IPropertyChangedEventArgs pointer in ptr.
+                ExceptionHelpers.ThrowExceptionForHR(((delegate* unmanaged[Stdcall]<IntPtr, IntPtr*, int>)(*(void***)ptr)[6])(ptr, &propertyName));
+                return new global::System.ComponentModel.PropertyChangedEventArgs(MarshalString.FromAbi(propertyName));
+            }
+            finally
+            {
+                MarshalString.DisposeAbi(propertyName);
+            }
+        }
+
+        public static unsafe void CopyManaged(global::System.ComponentModel.PropertyChangedEventArgs o, IntPtr dest)
+        {
+            *(IntPtr*)dest.ToPointer() = CreateMarshaler2(o).Detach();
+        }
+
+        public static IntPtr FromManaged(global::System.ComponentModel.PropertyChangedEventArgs value)
+        {
+            if (value is null)
+            {
+                return IntPtr.Zero;
+            }
+            return CreateMarshaler2(value).Detach();
+        }
+
+        public static void DisposeMarshaler(IObjectReference m) { m?.Dispose(); }
+        public static void DisposeAbi(IntPtr abi) { MarshalInspectable<object>.DisposeAbi(abi); }
+
+        public static unsafe MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.MarshalerArray CreateMarshalerArray(global::System.ComponentModel.PropertyChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.CreateMarshalerArray2(array, CreateMarshaler2);
+        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.GetAbiArray(box);
+        public static unsafe global::System.ComponentModel.PropertyChangedEventArgs[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.FromAbiArray(box, FromAbi);
+        public static void CopyAbiArray(global::System.ComponentModel.PropertyChangedEventArgs[] array, object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.CopyAbiArray(array, box, FromAbi);
+        public static (int length, IntPtr data) FromManagedArray(global::System.ComponentModel.PropertyChangedEventArgs[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.FromManagedArray(array, FromManaged);
+        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.MarshalerArray array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventArgs>.DisposeMarshalerArray(array);
+        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
+
+        public static string GetGuidSignature()
+        {
+            if (FeatureSwitches.UseWindowsUIXamlProjections)
+            {
+                return "rc(Windows.UI.Xaml.Data.NotifyPropertyChangedEventArgs;{4f33a9a0-5cf4-47a4-b16f-d7faaf17457e})";
+            }
+
+            return "rc(Microsoft.UI.Xaml.Data.NotifyPropertyChangedEventArgs;{4f33a9a0-5cf4-47a4-b16f-d7faaf17457e})";
+        }
+    }
+}
diff --git a/src/WinRT.Runtime/Projections/PropertyChangedEventHandler.cs b/src/WinRT.Runtime/Projections/PropertyChangedEventHandler.cs
index a38b988ea..9d821c102 100644
--- a/src/WinRT.Runtime/Projections/PropertyChangedEventHandler.cs
+++ b/src/WinRT.Runtime/Projections/PropertyChangedEventHandler.cs
@@ -1,200 +1,203 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT License.
-
-using System;
-using System.Collections.Concurrent;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using WinRT;
-using WinRT.Interop;
-
-namespace ABI.System.ComponentModel
-{
-    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
-    [Guid("E3DE52F6-1E32-5DA6-BB2D-B5B6096C962D")]
-#if EMBED
-    internal
-#else
-    public
-#endif
-    static class PropertyChangedEventHandler
-    {
-#if !NET
-        private unsafe delegate int Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e);
-#endif
-
-        private static readonly global::WinRT.Interop.IDelegateVftbl AbiToProjectionVftable;
-        public static readonly IntPtr AbiToProjectionVftablePtr;
-
-        static unsafe PropertyChangedEventHandler()
-        {
-            AbiToProjectionVftable = new global::WinRT.Interop.IDelegateVftbl
-            {
-                IUnknownVftbl = global::WinRT.Interop.IUnknownVftbl.AbiToProjectionVftbl,
-#if !NET
-                Invoke = Marshal.GetFunctionPointerForDelegate(AbiInvokeDelegate = (Abi_Invoke)Do_Abi_Invoke)
-#else
-                Invoke = (IntPtr)(delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)&Do_Abi_Invoke
-#endif
-            };
-            var nativeVftbl = ComWrappersSupport.AllocateVtableMemory(typeof(PropertyChangedEventHandler), sizeof(global::WinRT.Interop.IDelegateVftbl));
-            *(IDelegateVftbl*)nativeVftbl = AbiToProjectionVftable;
-            AbiToProjectionVftablePtr = nativeVftbl;
-            ComWrappersSupport.RegisterDelegateFactory(typeof(global::System.ComponentModel.PropertyChangedEventHandler), CreateRcw);
-        }
-
-        public static global::System.Delegate AbiInvokeDelegate { get; }
-
-        public static Guid IID => global::WinRT.Interop.IID.IID_PropertyChangedEventHandler;
-
-        public static unsafe IObjectReference CreateMarshaler(global::System.ComponentModel.PropertyChangedEventHandler managedDelegate) =>
-            managedDelegate is null ? null : MarshalDelegate.CreateMarshaler(managedDelegate, IID);
-
-        public static unsafe ObjectReferenceValue CreateMarshaler2(global::System.ComponentModel.PropertyChangedEventHandler managedDelegate) => 
-            MarshalDelegate.CreateMarshaler2(managedDelegate, IID);
-
-        public static IntPtr GetAbi(IObjectReference value) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.GetAbi(value);
-
-        public static unsafe global::System.ComponentModel.PropertyChangedEventHandler FromAbi(IntPtr nativeDelegate)
-        {
-            return MarshalDelegate.FromAbi<global::System.ComponentModel.PropertyChangedEventHandler>(nativeDelegate);
-        }
-
-        public static global::System.ComponentModel.PropertyChangedEventHandler CreateRcw(IntPtr ptr)
-        {
-            return new global::System.ComponentModel.PropertyChangedEventHandler(new NativeDelegateWrapper(ComWrappersSupport.GetObjectReferenceForInterface<IDelegateVftbl>(ptr, IID)).Invoke);
-        }
-
-#if !NET
-        [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
-        private sealed class NativeDelegateWrapper
-#else
-        private sealed class NativeDelegateWrapper : IWinRTObject
-#endif
-        {
-            private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;
-
-            public NativeDelegateWrapper(ObjectReference<global::WinRT.Interop.IDelegateVftbl> nativeDelegate)
-            {
-                _nativeDelegate = nativeDelegate;
-            }
-
-#if NET
-            IObjectReference IWinRTObject.NativeObject => _nativeDelegate;
-            bool IWinRTObject.HasUnwrappableNativeObject => true;
-            private volatile ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> _queryInterfaceCache;
-            private ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> MakeQueryInterfaceCache()
-            {
-                global::System.Threading.Interlocked.CompareExchange(ref _queryInterfaceCache, new ConcurrentDictionary<RuntimeTypeHandle, IObjectReference>(), null);
-                return _queryInterfaceCache;
-            }
-            ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> IWinRTObject.QueryInterfaceCache => _queryInterfaceCache ?? MakeQueryInterfaceCache();
-
-            private volatile ConcurrentDictionary<RuntimeTypeHandle, object> _additionalTypeData;
-            private ConcurrentDictionary<RuntimeTypeHandle, object> MakeAdditionalTypeData()
-            {
-                global::System.Threading.Interlocked.CompareExchange(ref _additionalTypeData, new ConcurrentDictionary<RuntimeTypeHandle, object>(), null);
-                return _additionalTypeData;
-            }
-            ConcurrentDictionary<RuntimeTypeHandle, object> IWinRTObject.AdditionalTypeData => _additionalTypeData ?? MakeAdditionalTypeData();
-#endif
-
-            public unsafe void Invoke(object sender, global::System.ComponentModel.PropertyChangedEventArgs e)
-            {
-                IntPtr ThisPtr = _nativeDelegate.ThisPtr;
-#if !NET
-                var abiInvoke = Marshal.GetDelegateForFunctionPointer<Abi_Invoke>(_nativeDelegate.Vftbl.Invoke);
-#else
-                var abiInvoke = (delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)(_nativeDelegate.Vftbl.Invoke);
-#endif
-                ObjectReferenceValue __sender = default;
-                ObjectReferenceValue __e = default;
-                try
-                {
-                    __sender = MarshalInspectable<object>.CreateMarshaler2(sender);
-                    __e = global::ABI.System.ComponentModel.PropertyChangedEventArgs.CreateMarshaler2(e);
-                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(abiInvoke(ThisPtr, MarshalInspectable<object>.GetAbi(__sender), MarshalInspectable<object>.GetAbi(__e)));
-                }
-                finally
-                {
-                    MarshalInspectable<object>.DisposeMarshaler(__sender);
-                    MarshalInspectable<object>.DisposeMarshaler(__e);
-                }
-            }
-        }
-
-        public static IntPtr FromManaged(global::System.ComponentModel.PropertyChangedEventHandler managedDelegate) => 
-            CreateMarshaler2(managedDelegate).Detach();
-
-        public static void DisposeMarshaler(IObjectReference value) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.DisposeMarshaler(value);
-
-        public static void DisposeAbi(IntPtr abi) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.DisposeAbi(abi);
-
-        public static unsafe MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.MarshalerArray CreateMarshalerArray(global::System.ComponentModel.PropertyChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.CreateMarshalerArray2(array, CreateMarshaler2);
-        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.GetAbiArray(box);
-        public static unsafe global::System.ComponentModel.PropertyChangedEventHandler[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.FromAbiArray(box, FromAbi);
-        public static void CopyAbiArray(global::System.ComponentModel.PropertyChangedEventHandler[] array, object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.CopyAbiArray(array, box, FromAbi);
-        public static (int length, IntPtr data) FromManagedArray(global::System.ComponentModel.PropertyChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.FromManagedArray(array, FromManaged);
-        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.MarshalerArray array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.DisposeMarshalerArray(array);
-        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
-
-#if NET
-        [UnmanagedCallersOnly(CallConvs = new[] { typeof(CallConvStdcall) })]
-#endif
-        private static unsafe int Do_Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e)
-        {
-            try
-            {
-#if NET
-                var invoke = ComWrappersSupport.FindObject<global::System.ComponentModel.PropertyChangedEventHandler>(thisPtr);
-                invoke.Invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.ComponentModel.PropertyChangedEventArgs.FromAbi(e));
-#else
-                global::WinRT.ComWrappersSupport.MarshalDelegateInvoke(thisPtr, (global::System.ComponentModel.PropertyChangedEventHandler invoke) =>
-                {
-                    invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.ComponentModel.PropertyChangedEventArgs.FromAbi(e));
-                });
-#endif
-            }
-            catch (global::System.Exception __exception__)
-            {
-                global::WinRT.ExceptionHelpers.SetErrorInfo(__exception__);
-                return global::WinRT.ExceptionHelpers.GetHRForException(__exception__);
-            }
-            return 0;
-        }
-    }
-
-    internal sealed unsafe class PropertyChangedEventSource : global::ABI.WinRT.Interop.EventSource<global::System.ComponentModel.PropertyChangedEventHandler>
-    {
-        internal PropertyChangedEventSource(
-            IObjectReference objectReference,
-#if NET
-            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, EventRegistrationToken*, int> addHandler,
-#else
-            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, out EventRegistrationToken, int> addHandler,
-#endif
-            delegate* unmanaged[Stdcall]<IntPtr, EventRegistrationToken, int> removeHandler)
-            : base(objectReference, addHandler, removeHandler)
-        {
-        }
-
-        protected override ObjectReferenceValue CreateMarshaler(global::System.ComponentModel.PropertyChangedEventHandler del) =>
-            PropertyChangedEventHandler.CreateMarshaler2(del);
-
-        protected override global::ABI.WinRT.Interop.EventSourceState<global::System.ComponentModel.PropertyChangedEventHandler> CreateEventSourceState() =>
-            new EventState(ObjectReference.ThisPtr, Index);
-
-        private sealed class EventState : global::ABI.WinRT.Interop.EventSourceState<global::System.ComponentModel.PropertyChangedEventHandler>
-        {
-            public EventState(IntPtr obj, int index)
-                : base(obj, index)
-            {
-            }
-
-            protected override global::System.ComponentModel.PropertyChangedEventHandler GetEventInvoke()
-            {
-                return (obj, e) => targetDelegate?.Invoke(obj, e);
-            }
-        }
-    }
-}
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Concurrent;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using WinRT;
+using WinRT.Interop;
+
+namespace ABI.System.ComponentModel
+{
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    [Guid("E3DE52F6-1E32-5DA6-BB2D-B5B6096C962D")]
+    [WuxMuxProjectedType]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class PropertyChangedEventHandler
+    {
+#if !NET
+        private unsafe delegate int Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e);
+#endif
+
+        private static readonly global::WinRT.Interop.IDelegateVftbl AbiToProjectionVftable;
+        public static readonly IntPtr AbiToProjectionVftablePtr;
+
+        static unsafe PropertyChangedEventHandler()
+        {
+            AbiToProjectionVftable = new global::WinRT.Interop.IDelegateVftbl
+            {
+                IUnknownVftbl = global::WinRT.Interop.IUnknownVftbl.AbiToProjectionVftbl,
+#if !NET
+                Invoke = Marshal.GetFunctionPointerForDelegate(AbiInvokeDelegate = (Abi_Invoke)Do_Abi_Invoke)
+#else
+                Invoke = (IntPtr)(delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)&Do_Abi_Invoke
+#endif
+            };
+            var nativeVftbl = ComWrappersSupport.AllocateVtableMemory(typeof(PropertyChangedEventHandler), sizeof(global::WinRT.Interop.IDelegateVftbl));
+            *(IDelegateVftbl*)nativeVftbl = AbiToProjectionVftable;
+            AbiToProjectionVftablePtr = nativeVftbl;
+            ComWrappersSupport.RegisterDelegateFactory(typeof(global::System.ComponentModel.PropertyChangedEventHandler), CreateRcw);
+        }
+
+        public static global::System.Delegate AbiInvokeDelegate { get; }
+
+        public static Guid IID => FeatureSwitches.UseWindowsUIXamlProjections
+            ? global::WinRT.Interop.IID.IID_WUX_PropertyChangedEventHandler
+            : global::WinRT.Interop.IID.IID_MUX_PropertyChangedEventHandler;
+
+        public static unsafe IObjectReference CreateMarshaler(global::System.ComponentModel.PropertyChangedEventHandler managedDelegate) =>
+            managedDelegate is null ? null : MarshalDelegate.CreateMarshaler(managedDelegate, IID);
+
+        public static unsafe ObjectReferenceValue CreateMarshaler2(global::System.ComponentModel.PropertyChangedEventHandler managedDelegate) => 
+            MarshalDelegate.CreateMarshaler2(managedDelegate, IID);
+
+        public static IntPtr GetAbi(IObjectReference value) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.GetAbi(value);
+
+        public static unsafe global::System.ComponentModel.PropertyChangedEventHandler FromAbi(IntPtr nativeDelegate)
+        {
+            return MarshalDelegate.FromAbi<global::System.ComponentModel.PropertyChangedEventHandler>(nativeDelegate);
+        }
+
+        public static global::System.ComponentModel.PropertyChangedEventHandler CreateRcw(IntPtr ptr)
+        {
+            return new global::System.ComponentModel.PropertyChangedEventHandler(new NativeDelegateWrapper(ComWrappersSupport.GetObjectReferenceForInterface<IDelegateVftbl>(ptr, IID)).Invoke);
+        }
+
+#if !NET
+        [global::WinRT.ObjectReferenceWrapper(nameof(_nativeDelegate))]
+        private sealed class NativeDelegateWrapper
+#else
+        private sealed class NativeDelegateWrapper : IWinRTObject
+#endif
+        {
+            private readonly ObjectReference<global::WinRT.Interop.IDelegateVftbl> _nativeDelegate;
+
+            public NativeDelegateWrapper(ObjectReference<global::WinRT.Interop.IDelegateVftbl> nativeDelegate)
+            {
+                _nativeDelegate = nativeDelegate;
+            }
+
+#if NET
+            IObjectReference IWinRTObject.NativeObject => _nativeDelegate;
+            bool IWinRTObject.HasUnwrappableNativeObject => true;
+            private volatile ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> _queryInterfaceCache;
+            private ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> MakeQueryInterfaceCache()
+            {
+                global::System.Threading.Interlocked.CompareExchange(ref _queryInterfaceCache, new ConcurrentDictionary<RuntimeTypeHandle, IObjectReference>(), null);
+                return _queryInterfaceCache;
+            }
+            ConcurrentDictionary<RuntimeTypeHandle, IObjectReference> IWinRTObject.QueryInterfaceCache => _queryInterfaceCache ?? MakeQueryInterfaceCache();
+
+            private volatile ConcurrentDictionary<RuntimeTypeHandle, object> _additionalTypeData;
+            private ConcurrentDictionary<RuntimeTypeHandle, object> MakeAdditionalTypeData()
+            {
+                global::System.Threading.Interlocked.CompareExchange(ref _additionalTypeData, new ConcurrentDictionary<RuntimeTypeHandle, object>(), null);
+                return _additionalTypeData;
+            }
+            ConcurrentDictionary<RuntimeTypeHandle, object> IWinRTObject.AdditionalTypeData => _additionalTypeData ?? MakeAdditionalTypeData();
+#endif
+
+            public unsafe void Invoke(object sender, global::System.ComponentModel.PropertyChangedEventArgs e)
+            {
+                IntPtr ThisPtr = _nativeDelegate.ThisPtr;
+#if !NET
+                var abiInvoke = Marshal.GetDelegateForFunctionPointer<Abi_Invoke>(_nativeDelegate.Vftbl.Invoke);
+#else
+                var abiInvoke = (delegate* unmanaged[Stdcall]<IntPtr, IntPtr, IntPtr, int>)(_nativeDelegate.Vftbl.Invoke);
+#endif
+                ObjectReferenceValue __sender = default;
+                ObjectReferenceValue __e = default;
+                try
+                {
+                    __sender = MarshalInspectable<object>.CreateMarshaler2(sender);
+                    __e = global::ABI.System.ComponentModel.PropertyChangedEventArgs.CreateMarshaler2(e);
+                    global::WinRT.ExceptionHelpers.ThrowExceptionForHR(abiInvoke(ThisPtr, MarshalInspectable<object>.GetAbi(__sender), MarshalInspectable<object>.GetAbi(__e)));
+                }
+                finally
+                {
+                    MarshalInspectable<object>.DisposeMarshaler(__sender);
+                    MarshalInspectable<object>.DisposeMarshaler(__e);
+                }
+            }
+        }
+
+        public static IntPtr FromManaged(global::System.ComponentModel.PropertyChangedEventHandler managedDelegate) => 
+            CreateMarshaler2(managedDelegate).Detach();
+
+        public static void DisposeMarshaler(IObjectReference value) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.DisposeMarshaler(value);
+
+        public static void DisposeAbi(IntPtr abi) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.DisposeAbi(abi);
+
+        public static unsafe MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.MarshalerArray CreateMarshalerArray(global::System.ComponentModel.PropertyChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.CreateMarshalerArray2(array, CreateMarshaler2);
+        public static (int length, IntPtr data) GetAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.GetAbiArray(box);
+        public static unsafe global::System.ComponentModel.PropertyChangedEventHandler[] FromAbiArray(object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.FromAbiArray(box, FromAbi);
+        public static void CopyAbiArray(global::System.ComponentModel.PropertyChangedEventHandler[] array, object box) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.CopyAbiArray(array, box, FromAbi);
+        public static (int length, IntPtr data) FromManagedArray(global::System.ComponentModel.PropertyChangedEventHandler[] array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.FromManagedArray(array, FromManaged);
+        public static void DisposeMarshalerArray(MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.MarshalerArray array) => MarshalInterfaceHelper<global::System.ComponentModel.PropertyChangedEventHandler>.DisposeMarshalerArray(array);
+        public static unsafe void DisposeAbiArray(object box) => MarshalInspectable<object>.DisposeAbiArray(box);
+
+#if NET
+        [UnmanagedCallersOnly(CallConvs = new[] { typeof(CallConvStdcall) })]
+#endif
+        private static unsafe int Do_Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e)
+        {
+            try
+            {
+#if NET
+                var invoke = ComWrappersSupport.FindObject<global::System.ComponentModel.PropertyChangedEventHandler>(thisPtr);
+                invoke.Invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.ComponentModel.PropertyChangedEventArgs.FromAbi(e));
+#else
+                global::WinRT.ComWrappersSupport.MarshalDelegateInvoke(thisPtr, (global::System.ComponentModel.PropertyChangedEventHandler invoke) =>
+                {
+                    invoke(MarshalInspectable<object>.FromAbi(sender), global::ABI.System.ComponentModel.PropertyChangedEventArgs.FromAbi(e));
+                });
+#endif
+            }
+            catch (global::System.Exception __exception__)
+            {
+                global::WinRT.ExceptionHelpers.SetErrorInfo(__exception__);
+                return global::WinRT.ExceptionHelpers.GetHRForException(__exception__);
+            }
+            return 0;
+        }
+    }
+
+    internal sealed unsafe class PropertyChangedEventSource : global::ABI.WinRT.Interop.EventSource<global::System.ComponentModel.PropertyChangedEventHandler>
+    {
+        internal PropertyChangedEventSource(
+            IObjectReference objectReference,
+#if NET
+            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, EventRegistrationToken*, int> addHandler,
+#else
+            delegate* unmanaged[Stdcall]<IntPtr, IntPtr, out EventRegistrationToken, int> addHandler,
+#endif
+            delegate* unmanaged[Stdcall]<IntPtr, EventRegistrationToken, int> removeHandler)
+            : base(objectReference, addHandler, removeHandler)
+        {
+        }
+
+        protected override ObjectReferenceValue CreateMarshaler(global::System.ComponentModel.PropertyChangedEventHandler del) =>
+            PropertyChangedEventHandler.CreateMarshaler2(del);
+
+        protected override global::ABI.WinRT.Interop.EventSourceState<global::System.ComponentModel.PropertyChangedEventHandler> CreateEventSourceState() =>
+            new EventState(ObjectReference.ThisPtr, Index);
+
+        private sealed class EventState : global::ABI.WinRT.Interop.EventSourceState<global::System.ComponentModel.PropertyChangedEventHandler>
+        {
+            public EventState(IntPtr obj, int index)
+                : base(obj, index)
+            {
+            }
+
+            protected override global::System.ComponentModel.PropertyChangedEventHandler GetEventInvoke()
+            {
+                return (obj, e) => targetDelegate?.Invoke(obj, e);
+            }
+        }
+    }
+}
diff --git a/src/cswinrt.sln b/src/cswinrt.sln
index bdc0d86a0..e6bb53157 100644
--- a/src/cswinrt.sln
+++ b/src/cswinrt.sln
@@ -160,6 +160,12 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "WinAppSDK", "Projections\Wi
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestLibrary", "Tests\FunctionalTests\TestLibrary\TestLibrary.csproj", "{335D51AC-1DCF-4487-A2BD-34CE2F17B3C4}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Windows.UI.Xaml", "Projections\Windows.UI.Xaml\Windows.UI.Xaml.csproj", "{E85F3614-79B6-4652-BDB0-64AF68874CE0}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "AuthoringWuxTest", "Tests\AuthoringWuxTest\AuthoringWuxTest.csproj", "{D60CFCAD-4A13-4047-91C8-9D7DF4753493}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "AuthoringWuxConsumptionTest", "Tests\AuthoringWuxConsumptionTest\AuthoringWuxConsumptionTest.vcxproj", "{A04A0416-5E35-4DD0-8226-63D941B28467}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|ARM = Debug|ARM
@@ -732,6 +738,54 @@ Global
 		{335D51AC-1DCF-4487-A2BD-34CE2F17B3C4}.Release|x64.Build.0 = Release|x64
 		{335D51AC-1DCF-4487-A2BD-34CE2F17B3C4}.Release|x86.ActiveCfg = Release|x86
 		{335D51AC-1DCF-4487-A2BD-34CE2F17B3C4}.Release|x86.Build.0 = Release|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|ARM.ActiveCfg = Debug|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|ARM.Build.0 = Debug|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|ARM64.ActiveCfg = Debug|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|ARM64.Build.0 = Debug|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|x64.ActiveCfg = Debug|x64
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|x64.Build.0 = Debug|x64
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|x86.ActiveCfg = Debug|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Debug|x86.Build.0 = Debug|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|ARM.ActiveCfg = Release|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|ARM.Build.0 = Release|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|ARM64.ActiveCfg = Release|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|ARM64.Build.0 = Release|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|x64.ActiveCfg = Release|x64
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|x64.Build.0 = Release|x64
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|x86.ActiveCfg = Release|x86
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0}.Release|x86.Build.0 = Release|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|ARM.ActiveCfg = Debug|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|ARM.Build.0 = Debug|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|ARM64.ActiveCfg = Debug|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|ARM64.Build.0 = Debug|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|x64.ActiveCfg = Debug|x64
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|x64.Build.0 = Debug|x64
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|x86.ActiveCfg = Debug|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Debug|x86.Build.0 = Debug|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|ARM.ActiveCfg = Release|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|ARM.Build.0 = Release|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|ARM64.ActiveCfg = Release|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|ARM64.Build.0 = Release|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|x64.ActiveCfg = Release|x64
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|x64.Build.0 = Release|x64
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|x86.ActiveCfg = Release|x86
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493}.Release|x86.Build.0 = Release|x86
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|ARM.ActiveCfg = Debug|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|ARM.Build.0 = Debug|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|ARM64.ActiveCfg = Debug|ARM64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|ARM64.Build.0 = Debug|ARM64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|x64.ActiveCfg = Debug|x64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|x64.Build.0 = Debug|x64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|x86.ActiveCfg = Debug|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Debug|x86.Build.0 = Debug|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|ARM.ActiveCfg = Release|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|ARM.Build.0 = Release|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|ARM64.ActiveCfg = Release|ARM64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|ARM64.Build.0 = Release|ARM64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|x64.ActiveCfg = Release|x64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|x64.Build.0 = Release|x64
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|x86.ActiveCfg = Release|Win32
+		{A04A0416-5E35-4DD0-8226-63D941B28467}.Release|x86.Build.0 = Release|Win32
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -777,6 +831,9 @@ Global
 		{C44DB047-5DF0-4732-98F4-A181D3AD8A7F} = {5ECC38F0-16FD-47E1-B8DC-8C474008AD55}
 		{7B803846-91AE-4B98-AC93-D3FCFB2DE5AA} = {6D41796B-9904-40B8-BBCB-40B2D1BAE44B}
 		{335D51AC-1DCF-4487-A2BD-34CE2F17B3C4} = {5ECC38F0-16FD-47E1-B8DC-8C474008AD55}
+		{E85F3614-79B6-4652-BDB0-64AF68874CE0} = {6D41796B-9904-40B8-BBCB-40B2D1BAE44B}
+		{D60CFCAD-4A13-4047-91C8-9D7DF4753493} = {CFB651EC-DAA4-4A11-ABCD-C77F90602EB5}
+		{A04A0416-5E35-4DD0-8226-63D941B28467} = {CFB651EC-DAA4-4A11-ABCD-C77F90602EB5}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {5AE8C9D7-2613-4E1A-A4F2-579BAC28D0A2}
diff --git a/src/cswinrt/code_writers.h b/src/cswinrt/code_writers.h
index 9836255cc..f4a49ea79 100644
--- a/src/cswinrt/code_writers.h
+++ b/src/cswinrt/code_writers.h
@@ -1480,7 +1480,7 @@ private % Make_%()
         if (event.Name() == "CanExecuteChanged" && event_type == "global::System.EventHandler<object>")
         {
             auto parent_type = w.write_temp("%", bind<write_type_name>(event.Parent(), typedef_name_type::NonProjected, true));
-            if (parent_type == "Microsoft.UI.Xaml.Input.ICommand")
+            if (parent_type == "Microsoft.UI.Xaml.Input.ICommand" || parent_type == "Windows.UI.Xaml.Input.ICommand")
             {
                 event_type = "global::System.EventHandler";
             }
diff --git a/src/cswinrt/cswinrt.vcxproj b/src/cswinrt/cswinrt.vcxproj
index 3613dc553..d5cc68b7e 100644
--- a/src/cswinrt/cswinrt.vcxproj
+++ b/src/cswinrt/cswinrt.vcxproj
@@ -111,6 +111,12 @@
     <None Include="strings\additions\Microsoft.UI.Xaml.Media\Microsoft.UI.Xaml.Media.cs" />
     <None Include="strings\additions\Microsoft.UI.Xaml\Microsoft.UI.Xaml.cs" />
     <None Include="strings\additions\Microsoft.UI.Xaml\Microsoft.UI.Xaml.SR.cs" />
+    <None Include="strings\additions\Windows.UI.Xaml.Controls.Primitives\Windows.UI.Xaml.Controls.Primitives.cs" />
+    <None Include="strings\additions\Windows.UI.Xaml.Media.Animation\Windows.UI.Xaml.Media.Animation.cs" />
+    <None Include="strings\additions\Windows.UI.Xaml.Media.Media3D\Windows.UI.Xaml.Media.Media3D.cs" />
+    <None Include="strings\additions\Windows.UI.Xaml.Media\Windows.UI.Xaml.Media.cs" />
+    <None Include="strings\additions\Windows.UI.Xaml\Windows.UI.Xaml.cs" />
+    <None Include="strings\additions\Windows.UI.Xaml\Windows.UI.Xaml.SR.cs" />
     <None Include="strings\additions\Windows.UI\Windows.UI.cs" />
     <None Include="strings\ComInteropHelpers.cs" />
     <None Include="strings\InitalizeProjection.cs" />
diff --git a/src/cswinrt/cswinrt.vcxproj.filters b/src/cswinrt/cswinrt.vcxproj.filters
index 1a891f07e..0f31137c2 100644
--- a/src/cswinrt/cswinrt.vcxproj.filters
+++ b/src/cswinrt/cswinrt.vcxproj.filters
@@ -51,6 +51,21 @@
     <Filter Include="strings\additions\Microsoft.UI.Xaml.Controls.Primitives">
       <UniqueIdentifier>{369a6d8a-43e6-48af-82c1-bb2e555909a4}</UniqueIdentifier>
     </Filter>
+    <Filter Include="strings\additions\Windows.UI.Xaml.Controls.Primitives">
+      <UniqueIdentifier>{22aeef74-f4df-40f4-a18f-8053ac54f966}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="strings\additions\Windows.UI.Xaml.Media.Animation">
+      <UniqueIdentifier>{bb545b29-ba72-4949-b044-790f57ba17a5}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="strings\additions\Windows.UI.Xaml.Media.Media3D">
+      <UniqueIdentifier>{8451fa83-9750-4aec-ae8c-a4149c4b98a6}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="strings\additions\Windows.UI.Xaml.Media">
+      <UniqueIdentifier>{98453be9-888b-4032-b5cd-4034b17197c9}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="strings\additions\Windows.UI.Xaml">
+      <UniqueIdentifier>{03980bb6-f657-4c07-a456-5b4774de5773}</UniqueIdentifier>
+    </Filter>
   </ItemGroup>
   <ItemGroup>
     <None Include="strings\InitalizeProjection.cs">
diff --git a/src/cswinrt/helpers.h b/src/cswinrt/helpers.h
index fcc3f7cc3..93b1ce916 100644
--- a/src/cswinrt/helpers.h
+++ b/src/cswinrt/helpers.h
@@ -670,7 +670,8 @@ namespace cswinrt
         } mapped_types[] =
         {
             // Make sure to keep this table consistent with the registrations in WinRT.Runtime/Projections.cs
-            // and the reverse mapping in WinRT.SourceGenerator/WinRTTypeWriter.cs.
+            // and the reverse mapping in WinRT.SourceGenerator/TypeMapper.cs.
+            // This table can include both the MUX and WUX types as only one will be selected at runtime.
             // NOTE: Must keep namespaces sorted (outer) and abi type names sorted (inner)
             { "Microsoft.UI.Xaml",
                 {
@@ -816,13 +817,92 @@ namespace cswinrt
                     { "IColorHelperStatics2" },
                 }
             },
-            // Temporary, until WinUI provides TypeName
+            { "Windows.UI.Xaml",
+                {
+                    { "CornerRadius", "Windows.UI.Xaml", "CornerRadius" },
+                    { "CornerRadiusHelper" },
+                    { "Duration", "Windows.UI.Xaml", "Duration" },
+                    { "DurationHelper" },
+                    { "DurationType", "Windows.UI.Xaml", "DurationType" },
+                    { "GridLength", "Windows.UI.Xaml", "GridLength" },
+                    { "GridLengthHelper" },
+                    { "GridUnitType", "Windows.UI.Xaml", "GridUnitType" },
+                    { "ICornerRadiusHelper" },
+                    { "ICornerRadiusHelperStatics" },
+                    { "IDurationHelper" },
+                    { "IDurationHelperStatics" },
+                    { "IGridLengthHelper" },
+                    { "IGridLengthHelperStatics" },
+                    { "IThicknessHelper" },
+                    { "IThicknessHelperStatics" },
+                    { "Thickness", "Windows.UI.Xaml", "Thickness" },
+                    { "ThicknessHelper" },
+                    { "IXamlServiceProvider", "System", "IServiceProvider" },
+                }
+            },
+            { "Windows.UI.Xaml.Controls.Primitives",
+                {
+                    { "GeneratorPosition", "Windows.UI.Xaml.Controls.Primitives", "GeneratorPosition" },
+                    { "GeneratorPositionHelper" },
+                    { "IGeneratorPositionHelper" },
+                    { "IGeneratorPositionHelperStatics" },
+                }
+            },
+            { "Windows.UI.Xaml.Data",
+                {
+                    { "DataErrorsChangedEventArgs", "System.ComponentModel", "DataErrorsChangedEventArgs" },
+                    { "INotifyDataErrorInfo", "System.ComponentModel", "INotifyDataErrorInfo", true, true },
+                    { "INotifyPropertyChanged", "System.ComponentModel", "INotifyPropertyChanged" },
+                    { "PropertyChangedEventArgs", "System.ComponentModel", "PropertyChangedEventArgs" },
+                    { "PropertyChangedEventHandler", "System.ComponentModel", "PropertyChangedEventHandler" },
+                }
+            },
+            { "Windows.UI.Xaml.Input",
+                {
+                    { "ICommand", "System.Windows.Input", "ICommand", true }
+                }
+            },
             { "Windows.UI.Xaml.Interop",
                 {
+                    { "IBindableIterable", "System.Collections", "IEnumerable", true, true },
+                    { "IBindableVector", "System.Collections", "IList", true, true },
+                    { "INotifyCollectionChanged", "System.Collections.Specialized", "INotifyCollectionChanged", true },
+                    { "NotifyCollectionChangedAction", "System.Collections.Specialized", "NotifyCollectionChangedAction" },
+                    { "NotifyCollectionChangedEventArgs", "System.Collections.Specialized", "NotifyCollectionChangedEventArgs", true },
+                    { "NotifyCollectionChangedEventHandler", "System.Collections.Specialized", "NotifyCollectionChangedEventHandler", true },
                     { "TypeKind", "Windows.UI.Xaml.Interop", "TypeKind", true },
                     { "TypeName", "System", "Type", true }
                 }
             },
+            { "Windows.UI.Xaml.Media",
+                {
+                    { "IMatrixHelper" },
+                    { "IMatrixHelperStatics" },
+                    { "Matrix", "Windows.UI.Xaml.Media", "Matrix" },
+                    { "MatrixHelper" },
+                }
+            },
+            { "Windows.UI.Xaml.Media.Animation",
+                {
+                    { "IKeyTimeHelper" },
+                    { "IKeyTimeHelperStatics" },
+                    { "IRepeatBehaviorHelper" },
+                    { "IRepeatBehaviorHelperStatics" },
+                    { "KeyTime", "Windows.UI.Xaml.Media.Animation", "KeyTime" },
+                    { "KeyTimeHelper" },
+                    { "RepeatBehavior", "Windows.UI.Xaml.Media.Animation", "RepeatBehavior" },
+                    { "RepeatBehaviorHelper" },
+                    { "RepeatBehaviorType", "Windows.UI.Xaml.Media.Animation", "RepeatBehaviorType" }
+                }
+            },
+            { "Windows.UI.Xaml.Media.Media3D",
+                {
+                    { "IMatrix3DHelper" },
+                    { "IMatrix3DHelperStatics" },
+                    { "Matrix3D", "Windows.UI.Xaml.Media.Media3D", "Matrix3D" },
+                    { "Matrix3DHelper" },
+                }
+            },
         };
 
         auto nsItr = std::lower_bound(std::begin(mapped_types), std::end(mapped_types), typeNamespace, [](auto&& v, std::string_view ns)
diff --git a/src/cswinrt/main.cpp b/src/cswinrt/main.cpp
index 8df213ac7..312b695e4 100644
--- a/src/cswinrt/main.cpp
+++ b/src/cswinrt/main.cpp
@@ -33,6 +33,7 @@ namespace cswinrt
         { "output", 0, 1, "<path>", "Location of generated projection" },
         { "include", 0, option::no_max, "<prefix>", "One or more prefixes to include in projection" },
         { "exclude", 0, option::no_max, "<prefix>", "One or more prefixes to exclude from projection" },
+        { "addition_exclude", 0, option::no_max, "<prefix>", "One or more namespace prefixes to exclude from the projection additions" },
         { "target", 0, 1, "<net8.0|net7.0|net6.0|netstandard2.0>", "Target TFM for projection. Omit for compatibility with .NET 6." },
         { "component", 0, 0, {}, "Generate component projection." },
         { "verbose", 0, 0, {}, "Show detailed progress information" },
@@ -113,6 +114,11 @@ Where <spec> is one or more of:
             settings.exclude.insert(exclude);
         }
 
+        for (auto&& addition_exclude : args.values("addition_exclude"))
+        {
+            settings.addition_exclude.insert(addition_exclude);
+        }
+
         settings.output_folder = std::filesystem::absolute(args.value("output", "output"));
         create_directories(settings.output_folder);
     }
@@ -137,6 +143,9 @@ Where <spec> is one or more of:
             cache c{ get_files_to_cache() };
             settings.filter = { settings.include, settings.exclude };
 
+            // Include all additions for included namespaces by default
+            settings.addition_filter = { settings.include, settings.addition_exclude };
+
             std::set<TypeDef> componentActivatableClasses;
             if (settings.component)
             {
@@ -322,7 +331,7 @@ Where <spec> is one or more of:
                             // Custom additions to namespaces
                             for (auto addition : strings::additions)
                             {
-                                if (ns == addition.name)
+                                if (ns == addition.name && settings.addition_filter.includes(ns))
                                 {
                                     w.write(addition.value);
                                 }
diff --git a/src/cswinrt/settings.h b/src/cswinrt/settings.h
index efdb304eb..b095f5d33 100644
--- a/src/cswinrt/settings.h
+++ b/src/cswinrt/settings.h
@@ -9,7 +9,9 @@ namespace cswinrt
         bool verbose{};
         std::set<std::string> include;
         std::set<std::string> exclude;
+        std::set<std::string> addition_exclude;
         winmd::reader::filter filter;
+        winmd::reader::filter addition_filter;
         bool netstandard_compat{};
         bool net7_0_or_greater{};
         bool component{};
diff --git a/src/cswinrt/strings/additions/Windows.UI.Xaml.Controls/Windows.UI.Xaml.Controls.Primitives.cs b/src/cswinrt/strings/additions/Windows.UI.Xaml.Controls/Windows.UI.Xaml.Controls.Primitives.cs
new file mode 100644
index 000000000..ec28e9295
--- /dev/null
+++ b/src/cswinrt/strings/additions/Windows.UI.Xaml.Controls/Windows.UI.Xaml.Controls.Primitives.cs
@@ -0,0 +1,73 @@
+
+namespace Windows.UI.Xaml.Controls.Primitives
+{
+    using global::Windows.Foundation;
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Controls.Primitives.GeneratorPosition))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct GeneratorPosition
+    {
+        private int _index;
+        private int _offset;
+
+        public int Index { get { return _index; } set { _index = value; } }
+        public int Offset { get { return _offset; } set { _offset = value; } }
+
+        public GeneratorPosition(int index, int offset)
+        {
+            _index = index;
+            _offset = offset;
+        }
+
+        public override int GetHashCode()
+        {
+            return _index.GetHashCode() + _offset.GetHashCode();
+        }
+
+        public override string ToString()
+        {
+            return string.Concat("GeneratorPosition (", _index.ToString(global::System.Globalization.CultureInfo.InvariantCulture), ",", _offset.ToString(global::System.Globalization.CultureInfo.InvariantCulture), ")");
+        }
+
+        public override bool Equals(object o)
+        {
+            if (o is GeneratorPosition)
+            {
+                GeneratorPosition that = (GeneratorPosition)o;
+                return _index == that._index &&
+                        _offset == that._offset;
+            }
+            return false;
+        }
+
+        public static bool operator ==(GeneratorPosition gp1, GeneratorPosition gp2)
+        {
+            return gp1._index == gp2._index &&
+                    gp1._offset == gp2._offset;
+        }
+
+        public static bool operator !=(GeneratorPosition gp1, GeneratorPosition gp2)
+        {
+            return !(gp1 == gp2);
+        }
+    }
+}
+
+namespace ABI.Windows.UI.Xaml.Controls.Primitives
+{
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class GeneratorPosition
+    {
+        public static string GetGuidSignature() => $"struct(Windows.UI.Xaml.Controls.Primitives.GeneratorPosition;i4;i4)";
+    }
+}
diff --git a/src/cswinrt/strings/additions/Windows.UI.Xaml.Media.Animation/Windows.UI.Xaml.Media.Animation.cs b/src/cswinrt/strings/additions/Windows.UI.Xaml.Media.Animation/Windows.UI.Xaml.Media.Animation.cs
new file mode 100644
index 000000000..259898959
--- /dev/null
+++ b/src/cswinrt/strings/additions/Windows.UI.Xaml.Media.Animation/Windows.UI.Xaml.Media.Animation.cs
@@ -0,0 +1,326 @@
+
+namespace Windows.UI.Xaml.Media.Animation
+{
+    using global::Windows.Foundation;
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Media.Animation.KeyTime))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct KeyTime
+    {
+        private TimeSpan _timeSpan;
+
+        public static KeyTime FromTimeSpan(TimeSpan timeSpan)
+        {
+            if (timeSpan < TimeSpan.Zero)
+            {
+                throw new ArgumentOutOfRangeException(nameof(timeSpan));
+            }
+
+            KeyTime keyTime = default;
+
+            keyTime._timeSpan = timeSpan;
+
+            return keyTime;
+        }
+
+        public static bool Equals(KeyTime keyTime1, KeyTime keyTime2)
+        {
+            return (keyTime1._timeSpan == keyTime2._timeSpan);
+        }
+
+        public static bool operator ==(KeyTime keyTime1, KeyTime keyTime2)
+        {
+            return KeyTime.Equals(keyTime1, keyTime2);
+        }
+
+        public static bool operator !=(KeyTime keyTime1, KeyTime keyTime2)
+        {
+            return !KeyTime.Equals(keyTime1, keyTime2);
+        }
+
+        public bool Equals(KeyTime value)
+        {
+            return KeyTime.Equals(this, value);
+        }
+
+        public override bool Equals(object value)
+        {
+            return value is KeyTime && this == (KeyTime)value;
+        }
+
+        public override int GetHashCode()
+        {
+            return _timeSpan.GetHashCode();
+        }
+
+        public override string ToString()
+        {
+            return _timeSpan.ToString();
+        }
+
+        public static implicit operator KeyTime(TimeSpan timeSpan)
+        {
+            return KeyTime.FromTimeSpan(timeSpan);
+        }
+
+        public TimeSpan TimeSpan
+        {
+            get
+            {
+                return _timeSpan;
+            }
+        }
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    enum RepeatBehaviorType
+    {
+        Count,
+        Duration,
+        Forever
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Media.Animation.RepeatBehavior))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct RepeatBehavior : IFormattable
+    {
+        private double _Count;
+        private TimeSpan _Duration;
+        private RepeatBehaviorType _Type;
+
+        internal static bool IsFinite(double value)
+        {
+            return !(double.IsNaN(value) || double.IsInfinity(value));
+        }
+
+        public RepeatBehavior(double count)
+        {
+            if (!IsFinite(count) || count < 0.0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(count));
+            }
+
+            _Duration = new TimeSpan(0);
+            _Count = count;
+            _Type = RepeatBehaviorType.Count;
+        }
+
+        public RepeatBehavior(TimeSpan duration)
+        {
+            if (duration < new TimeSpan(0))
+            {
+                throw new ArgumentOutOfRangeException(nameof(duration));
+            }
+
+            _Duration = duration;
+            _Count = 0.0;
+            _Type = RepeatBehaviorType.Duration;
+        }
+
+        public static RepeatBehavior Forever
+        {
+            get
+            {
+                RepeatBehavior forever = default;
+                forever.Type = RepeatBehaviorType.Forever;
+
+                return forever;
+            }
+        }
+
+        public bool HasCount
+        {
+            get
+            {
+                return Type == RepeatBehaviorType.Count;
+            }
+        }
+
+        public bool HasDuration
+        {
+            get
+            {
+                return Type == RepeatBehaviorType.Duration;
+            }
+        }
+
+        public double Count
+        {
+            get { return _Count; }
+            set { _Count = value; }
+        }
+
+        public TimeSpan Duration
+        {
+            get { return _Duration; }
+            set { _Duration = value; }
+        }
+
+        public RepeatBehaviorType Type
+        {
+            get { return _Type; }
+            set { _Type = value; }
+        }
+
+        public override string ToString()
+        {
+            return InternalToString(null, null);
+        }
+
+        public string ToString(IFormatProvider formatProvider)
+        {
+            return InternalToString(null, formatProvider);
+        }
+
+        string IFormattable.ToString(string format, IFormatProvider formatProvider)
+        {
+            return InternalToString(format, formatProvider);
+        }
+
+        internal string InternalToString(string format, IFormatProvider formatProvider)
+        {
+            switch (_Type)
+            {
+                case RepeatBehaviorType.Forever:
+
+                    return "Forever";
+
+                case RepeatBehaviorType.Count:
+
+                    global::System.Text.StringBuilder sb = new global::System.Text.StringBuilder();
+
+                    sb.AppendFormat(
+                        formatProvider,
+                        "{0:" + format + "}x",
+                        _Count);
+
+                    return sb.ToString();
+
+                case RepeatBehaviorType.Duration:
+
+                    return _Duration.ToString();
+
+                default:
+                    return string.Empty;
+            }
+        }
+
+        public override bool Equals(object value)
+        {
+            if (value is RepeatBehavior)
+            {
+                return this.Equals((RepeatBehavior)value);
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        public bool Equals(RepeatBehavior repeatBehavior)
+        {
+            if (_Type == repeatBehavior._Type)
+            {
+                return _Type switch
+                {
+                    RepeatBehaviorType.Forever => true,
+                    RepeatBehaviorType.Count => _Count == repeatBehavior._Count,
+                    RepeatBehaviorType.Duration => _Duration == repeatBehavior._Duration,
+                    _ => false,
+                };
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        public static bool Equals(RepeatBehavior repeatBehavior1, RepeatBehavior repeatBehavior2)
+        {
+            return repeatBehavior1.Equals(repeatBehavior2);
+        }
+
+        public override int GetHashCode()
+        {
+            return _Type switch
+            {
+                RepeatBehaviorType.Count => _Count.GetHashCode(),
+                RepeatBehaviorType.Duration => _Duration.GetHashCode(),
+
+                // We try to choose an unlikely hash code value for Forever.
+                // All Forevers need to return the same hash code value.
+                RepeatBehaviorType.Forever => int.MaxValue - 42,
+
+                _ => base.GetHashCode(),
+            };
+        }
+
+        public static bool operator ==(RepeatBehavior repeatBehavior1, RepeatBehavior repeatBehavior2)
+        {
+            return repeatBehavior1.Equals(repeatBehavior2);
+        }
+
+        public static bool operator !=(RepeatBehavior repeatBehavior1, RepeatBehavior repeatBehavior2)
+        {
+            return !repeatBehavior1.Equals(repeatBehavior2);
+        }
+    }
+}
+
+namespace ABI.Windows.UI.Xaml.Media.Animation
+{
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class KeyTime
+    {
+        public static string GetGuidSignature()
+        {
+            string timeSpanSignature = global::WinRT.GuidGenerator.GetSignature(typeof(global::System.TimeSpan));
+            return $"struct(Windows.UI.Xaml.Media.Animation.KeyTime;{timeSpanSignature})";
+        }
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class RepeatBehavior
+    {
+        public static string GetGuidSignature()
+        {
+            string timeSpanSignature = global::WinRT.GuidGenerator.GetSignature(typeof(global::System.TimeSpan));
+            return $"struct(Windows.UI.Xaml.Media.Animation.RepeatBehavior;f8;{timeSpanSignature};{RepeatBehaviorType.GetGuidSignature()})";
+        }
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class RepeatBehaviorType
+    {
+        public static string GetGuidSignature() => "enum(Windows.UI.Xaml.Media.Animation.RepeatBehaviorType;i4)";
+    }
+}
diff --git a/src/cswinrt/strings/additions/Windows.UI.Xaml.Media.Media3D/Windows.UI.Xaml.Media.Media3D.cs b/src/cswinrt/strings/additions/Windows.UI.Xaml.Media.Media3D/Windows.UI.Xaml.Media.Media3D.cs
new file mode 100644
index 000000000..98dfb069e
--- /dev/null
+++ b/src/cswinrt/strings/additions/Windows.UI.Xaml.Media.Media3D/Windows.UI.Xaml.Media.Media3D.cs
@@ -0,0 +1,711 @@
+
+namespace Windows.UI.Xaml.Media.Media3D
+{
+    using global::Windows.Foundation;
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Media.Media3D.Matrix3D))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct Matrix3D : IFormattable
+    {
+        // Assuming this matrix has fourth column of 0,0,0,1 and isn't identity this function:
+        // Returns false if HasInverse is false, otherwise inverts the matrix.
+        private bool NormalizedAffineInvert()
+        {
+            double z20 = _m12 * _m23 - _m22 * _m13;
+            double z10 = _m32 * _m13 - _m12 * _m33;
+            double z00 = _m22 * _m33 - _m32 * _m23;
+            double det = _m31 * z20 + _m21 * z10 + _m11 * z00;
+
+            if (IsZero(det))
+            {
+                return false;
+            }
+
+            // Compute 3x3 non-zero cofactors for the 2nd column
+            double z21 = _m21 * _m13 - _m11 * _m23;
+            double z11 = _m11 * _m33 - _m31 * _m13;
+            double z01 = _m31 * _m23 - _m21 * _m33;
+
+            // Compute all six 2x2 determinants of 1st two columns
+            double y01 = _m11 * _m22 - _m21 * _m12;
+            double y02 = _m11 * _m32 - _m31 * _m12;
+            double y03 = _m11 * _offsetY - _offsetX * _m12;
+            double y12 = _m21 * _m32 - _m31 * _m22;
+            double y13 = _m21 * _offsetY - _offsetX * _m22;
+            double y23 = _m31 * _offsetY - _offsetX * _m32;
+
+            // Compute all non-zero and non-one 3x3 cofactors for 2nd
+            // two columns
+            double z23 = _m23 * y03 - _offsetZ * y01 - _m13 * y13;
+            double z13 = _m13 * y23 - _m33 * y03 + _offsetZ * y02;
+            double z03 = _m33 * y13 - _offsetZ * y12 - _m23 * y23;
+            double z22 = y01;
+            double z12 = -y02;
+            double z02 = y12;
+
+            double rcp = 1.0 / det;
+
+            // Multiply all 3x3 cofactors by reciprocal & transpose
+            _m11 = (z00 * rcp);
+            _m12 = (z10 * rcp);
+            _m13 = (z20 * rcp);
+
+            _m21 = (z01 * rcp);
+            _m22 = (z11 * rcp);
+            _m23 = (z21 * rcp);
+
+            _m31 = (z02 * rcp);
+            _m32 = (z12 * rcp);
+            _m33 = (z22 * rcp);
+
+            _offsetX = (z03 * rcp);
+            _offsetY = (z13 * rcp);
+            _offsetZ = (z23 * rcp);
+
+            return true;
+        }
+
+        // RETURNS true if has inverse & invert was done.  Otherwise returns false & leaves matrix unchanged.
+        private bool InvertCore()
+        {
+            if (IsAffine)
+            {
+                return NormalizedAffineInvert();
+            }
+
+            // compute all six 2x2 determinants of 2nd two columns
+            double y01 = _m13 * _m24 - _m23 * _m14;
+            double y02 = _m13 * _m34 - _m33 * _m14;
+            double y03 = _m13 * _m44 - _offsetZ * _m14;
+            double y12 = _m23 * _m34 - _m33 * _m24;
+            double y13 = _m23 * _m44 - _offsetZ * _m24;
+            double y23 = _m33 * _m44 - _offsetZ * _m34;
+
+            // Compute 3x3 cofactors for 1st the column
+            double z30 = _m22 * y02 - _m32 * y01 - _m12 * y12;
+            double z20 = _m12 * y13 - _m22 * y03 + _offsetY * y01;
+            double z10 = _m32 * y03 - _offsetY * y02 - _m12 * y23;
+            double z00 = _m22 * y23 - _m32 * y13 + _offsetY * y12;
+
+            // Compute 4x4 determinant
+            double det = _offsetX * z30 + _m31 * z20 + _m21 * z10 + _m11 * z00;
+
+            if (IsZero(det))
+            {
+                return false;
+            }
+
+            // Compute 3x3 cofactors for the 2nd column
+            double z31 = _m11 * y12 - _m21 * y02 + _m31 * y01;
+            double z21 = _m21 * y03 - _offsetX * y01 - _m11 * y13;
+            double z11 = _m11 * y23 - _m31 * y03 + _offsetX * y02;
+            double z01 = _m31 * y13 - _offsetX * y12 - _m21 * y23;
+
+            // Compute all six 2x2 determinants of 1st two columns
+            y01 = _m11 * _m22 - _m21 * _m12;
+            y02 = _m11 * _m32 - _m31 * _m12;
+            y03 = _m11 * _offsetY - _offsetX * _m12;
+            y12 = _m21 * _m32 - _m31 * _m22;
+            y13 = _m21 * _offsetY - _offsetX * _m22;
+            y23 = _m31 * _offsetY - _offsetX * _m32;
+
+            // Compute all 3x3 cofactors for 2nd two columns
+            double z33 = _m13 * y12 - _m23 * y02 + _m33 * y01;
+            double z23 = _m23 * y03 - _offsetZ * y01 - _m13 * y13;
+            double z13 = _m13 * y23 - _m33 * y03 + _offsetZ * y02;
+            double z03 = _m33 * y13 - _offsetZ * y12 - _m23 * y23;
+            double z32 = _m24 * y02 - _m34 * y01 - _m14 * y12;
+            double z22 = _m14 * y13 - _m24 * y03 + _m44 * y01;
+            double z12 = _m34 * y03 - _m44 * y02 - _m14 * y23;
+            double z02 = _m24 * y23 - _m34 * y13 + _m44 * y12;
+
+            double rcp = 1.0 / det;
+
+            // Multiply all 3x3 cofactors by reciprocal & transpose
+            _m11 = (z00 * rcp);
+            _m12 = (z10 * rcp);
+            _m13 = (z20 * rcp);
+            _m14 = (z30 * rcp);
+
+            _m21 = (z01 * rcp);
+            _m22 = (z11 * rcp);
+            _m23 = (z21 * rcp);
+            _m24 = (z31 * rcp);
+
+            _m31 = (z02 * rcp);
+            _m32 = (z12 * rcp);
+            _m33 = (z22 * rcp);
+            _m34 = (z32 * rcp);
+
+            _offsetX = (z03 * rcp);
+            _offsetY = (z13 * rcp);
+            _offsetZ = (z23 * rcp);
+            _m44 = (z33 * rcp);
+
+            return true;
+        }
+
+        public Matrix3D(double m11, double m12, double m13, double m14,
+                        double m21, double m22, double m23, double m24,
+                        double m31, double m32, double m33, double m34,
+                        double offsetX, double offsetY, double offsetZ, double m44)
+        {
+            _m11 = m11;
+            _m12 = m12;
+            _m13 = m13;
+            _m14 = m14;
+            _m21 = m21;
+            _m22 = m22;
+            _m23 = m23;
+            _m24 = m24;
+            _m31 = m31;
+            _m32 = m32;
+            _m33 = m33;
+            _m34 = m34;
+            _offsetX = offsetX;
+            _offsetY = offsetY;
+            _offsetZ = offsetZ;
+            _m44 = m44;
+        }
+
+        // the transform is identity by default
+        // Actually fill in the fields - some (internal) code uses the fields directly for perf.
+        private static Matrix3D s_identity = CreateIdentity();
+
+        public double M11
+        {
+            get
+            {
+                return _m11;
+            }
+            set
+            {
+                _m11 = value;
+            }
+        }
+
+        public double M12
+        {
+            get
+            {
+                return _m12;
+            }
+            set
+            {
+                _m12 = value;
+            }
+        }
+
+        public double M13
+        {
+            get
+            {
+                return _m13;
+            }
+            set
+            {
+                _m13 = value;
+            }
+        }
+
+        public double M14
+        {
+            get
+            {
+                return _m14;
+            }
+            set
+            {
+                _m14 = value;
+            }
+        }
+
+        public double M21
+        {
+            get
+            {
+                return _m21;
+            }
+            set
+            {
+                _m21 = value;
+            }
+        }
+
+        public double M22
+        {
+            get
+            {
+                return _m22;
+            }
+            set
+            {
+                _m22 = value;
+            }
+        }
+
+        public double M23
+        {
+            get
+            {
+                return _m23;
+            }
+            set
+            {
+                _m23 = value;
+            }
+        }
+
+        public double M24
+        {
+            get
+            {
+                return _m24;
+            }
+            set
+            {
+                _m24 = value;
+            }
+        }
+
+        public double M31
+        {
+            get
+            {
+                return _m31;
+            }
+            set
+            {
+                _m31 = value;
+            }
+        }
+
+        public double M32
+        {
+            get
+            {
+                return _m32;
+            }
+            set
+            {
+                _m32 = value;
+            }
+        }
+
+        public double M33
+        {
+            get
+            {
+                return _m33;
+            }
+            set
+            {
+                _m33 = value;
+            }
+        }
+
+        public double M34
+        {
+            get
+            {
+                return _m34;
+            }
+            set
+            {
+                _m34 = value;
+            }
+        }
+
+        public double OffsetX
+        {
+            get
+            {
+                return _offsetX;
+            }
+            set
+            {
+                _offsetX = value;
+            }
+        }
+
+        public double OffsetY
+        {
+            get
+            {
+                return _offsetY;
+            }
+            set
+            {
+                _offsetY = value;
+            }
+        }
+
+        public double OffsetZ
+        {
+            get
+            {
+                return _offsetZ;
+            }
+            set
+            {
+                _offsetZ = value;
+            }
+        }
+
+        public double M44
+        {
+            get
+            {
+                return _m44;
+            }
+            set
+            {
+                _m44 = value;
+            }
+        }
+
+        public static Matrix3D Identity
+        {
+            get
+            {
+                return s_identity;
+            }
+        }
+
+        public bool IsIdentity
+        {
+            get
+            {
+                return (_m11 == 1 && _m12 == 0 && _m13 == 0 && _m14 == 0 &&
+                         _m21 == 0 && _m22 == 1 && _m23 == 0 && _m24 == 0 &&
+                         _m31 == 0 && _m32 == 0 && _m33 == 1 && _m34 == 0 &&
+                         _offsetX == 0 && _offsetY == 0 && _offsetZ == 0 && _m44 == 1);
+            }
+        }
+
+        public override string ToString()
+        {
+            // Delegate to the internal method which implements all ToString calls.
+            return ConvertToString(null /* format string */, null /* format provider */);
+        }
+
+        public string ToString(IFormatProvider provider)
+        {
+            // Delegate to the internal method which implements all ToString calls.
+            return ConvertToString(null /* format string */, provider);
+        }
+
+        string IFormattable.ToString(string format, IFormatProvider provider)
+        {
+            // Delegate to the internal method which implements all ToString calls.
+            return ConvertToString(format, provider);
+        }
+
+        private string ConvertToString(string format, IFormatProvider provider)
+        {
+            if (IsIdentity)
+            {
+                return "Identity";
+            }
+
+            // Helper to get the numeric list separator for a given culture.
+            char separator = TokenizerHelper.GetNumericListSeparator(provider);
+            return string.Format(provider,
+                                 "{1:" + format + "}{0}{2:" + format + "}{0}{3:" + format + "}{0}{4:" + format + "}{0}{5:" + format +
+                                 "}{0}{6:" + format + "}{0}{7:" + format + "}{0}{8:" + format + "}{0}{9:" + format + "}{0}{10:" + format +
+                                 "}{0}{11:" + format + "}{0}{12:" + format + "}{0}{13:" + format + "}{0}{14:" + format + "}{0}{15:" + format + "}{0}{16:" + format + "}",
+                                 separator,
+                                 _m11, _m12, _m13, _m14,
+                                 _m21, _m22, _m23, _m24,
+                                 _m31, _m32, _m33, _m34,
+                                 _offsetX, _offsetY, _offsetZ, _m44);
+        }
+
+        public override int GetHashCode()
+        {
+            // Perform field-by-field XOR of HashCodes
+            return M11.GetHashCode() ^
+                   M12.GetHashCode() ^
+                   M13.GetHashCode() ^
+                   M14.GetHashCode() ^
+                   M21.GetHashCode() ^
+                   M22.GetHashCode() ^
+                   M23.GetHashCode() ^
+                   M24.GetHashCode() ^
+                   M31.GetHashCode() ^
+                   M32.GetHashCode() ^
+                   M33.GetHashCode() ^
+                   M34.GetHashCode() ^
+                   OffsetX.GetHashCode() ^
+                   OffsetY.GetHashCode() ^
+                   OffsetZ.GetHashCode() ^
+                   M44.GetHashCode();
+        }
+
+        public override bool Equals(object o)
+        {
+            return o is Matrix3D && Matrix3D.Equals(this, (Matrix3D)o);
+        }
+
+        public bool Equals(Matrix3D value)
+        {
+            return Matrix3D.Equals(this, value);
+        }
+
+        public static bool operator ==(Matrix3D matrix1, Matrix3D matrix2)
+        {
+            return matrix1.M11 == matrix2.M11 &&
+                   matrix1.M12 == matrix2.M12 &&
+                   matrix1.M13 == matrix2.M13 &&
+                   matrix1.M14 == matrix2.M14 &&
+                   matrix1.M21 == matrix2.M21 &&
+                   matrix1.M22 == matrix2.M22 &&
+                   matrix1.M23 == matrix2.M23 &&
+                   matrix1.M24 == matrix2.M24 &&
+                   matrix1.M31 == matrix2.M31 &&
+                   matrix1.M32 == matrix2.M32 &&
+                   matrix1.M33 == matrix2.M33 &&
+                   matrix1.M34 == matrix2.M34 &&
+                   matrix1.OffsetX == matrix2.OffsetX &&
+                   matrix1.OffsetY == matrix2.OffsetY &&
+                   matrix1.OffsetZ == matrix2.OffsetZ &&
+                   matrix1.M44 == matrix2.M44;
+        }
+
+        public static bool operator !=(Matrix3D matrix1, Matrix3D matrix2)
+        {
+            return !(matrix1 == matrix2);
+        }
+
+        public static Matrix3D operator *(Matrix3D matrix1, Matrix3D matrix2)
+        {
+            Matrix3D matrix3D = default;
+
+            matrix3D.M11 = matrix1.M11 * matrix2.M11 +
+                           matrix1.M12 * matrix2.M21 +
+                           matrix1.M13 * matrix2.M31 +
+                           matrix1.M14 * matrix2.OffsetX;
+            matrix3D.M12 = matrix1.M11 * matrix2.M12 +
+                           matrix1.M12 * matrix2.M22 +
+                           matrix1.M13 * matrix2.M32 +
+                           matrix1.M14 * matrix2.OffsetY;
+            matrix3D.M13 = matrix1.M11 * matrix2.M13 +
+                           matrix1.M12 * matrix2.M23 +
+                           matrix1.M13 * matrix2.M33 +
+                           matrix1.M14 * matrix2.OffsetZ;
+            matrix3D.M14 = matrix1.M11 * matrix2.M14 +
+                           matrix1.M12 * matrix2.M24 +
+                           matrix1.M13 * matrix2.M34 +
+                           matrix1.M14 * matrix2.M44;
+            matrix3D.M21 = matrix1.M21 * matrix2.M11 +
+                           matrix1.M22 * matrix2.M21 +
+                           matrix1.M23 * matrix2.M31 +
+                           matrix1.M24 * matrix2.OffsetX;
+            matrix3D.M22 = matrix1.M21 * matrix2.M12 +
+                           matrix1.M22 * matrix2.M22 +
+                           matrix1.M23 * matrix2.M32 +
+                           matrix1.M24 * matrix2.OffsetY;
+            matrix3D.M23 = matrix1.M21 * matrix2.M13 +
+                           matrix1.M22 * matrix2.M23 +
+                           matrix1.M23 * matrix2.M33 +
+                           matrix1.M24 * matrix2.OffsetZ;
+            matrix3D.M24 = matrix1.M21 * matrix2.M14 +
+                           matrix1.M22 * matrix2.M24 +
+                           matrix1.M23 * matrix2.M34 +
+                           matrix1.M24 * matrix2.M44;
+            matrix3D.M31 = matrix1.M31 * matrix2.M11 +
+                           matrix1.M32 * matrix2.M21 +
+                           matrix1.M33 * matrix2.M31 +
+                           matrix1.M34 * matrix2.OffsetX;
+            matrix3D.M32 = matrix1.M31 * matrix2.M12 +
+                           matrix1.M32 * matrix2.M22 +
+                           matrix1.M33 * matrix2.M32 +
+                           matrix1.M34 * matrix2.OffsetY;
+            matrix3D.M33 = matrix1.M31 * matrix2.M13 +
+                           matrix1.M32 * matrix2.M23 +
+                           matrix1.M33 * matrix2.M33 +
+                           matrix1.M34 * matrix2.OffsetZ;
+            matrix3D.M34 = matrix1.M31 * matrix2.M14 +
+                           matrix1.M32 * matrix2.M24 +
+                           matrix1.M33 * matrix2.M34 +
+                           matrix1.M34 * matrix2.M44;
+            matrix3D.OffsetX = matrix1.OffsetX * matrix2.M11 +
+                           matrix1.OffsetY * matrix2.M21 +
+                           matrix1.OffsetZ * matrix2.M31 +
+                           matrix1.M44 * matrix2.OffsetX;
+            matrix3D.OffsetY = matrix1.OffsetX * matrix2.M12 +
+                           matrix1.OffsetY * matrix2.M22 +
+                           matrix1.OffsetZ * matrix2.M32 +
+                           matrix1.M44 * matrix2.OffsetY;
+            matrix3D.OffsetZ = matrix1.OffsetX * matrix2.M13 +
+                           matrix1.OffsetY * matrix2.M23 +
+                           matrix1.OffsetZ * matrix2.M33 +
+                           matrix1.M44 * matrix2.OffsetZ;
+            matrix3D.M44 = matrix1.OffsetX * matrix2.M14 +
+                           matrix1.OffsetY * matrix2.M24 +
+                           matrix1.OffsetZ * matrix2.M34 +
+                           matrix1.M44 * matrix2.M44;
+
+            // matrix3D._type is not set.
+
+            return matrix3D;
+        }
+
+        public bool HasInverse
+        {
+            get
+            {
+                return !IsZero(Determinant);
+            }
+        }
+
+        public void Invert()
+        {
+            if (!InvertCore())
+            {
+                throw new InvalidOperationException();
+            }
+        }
+
+        private static Matrix3D CreateIdentity()
+        {
+            Matrix3D matrix3D = default;
+            matrix3D.SetMatrix(1, 0, 0, 0,
+                               0, 1, 0, 0,
+                               0, 0, 1, 0,
+                               0, 0, 0, 1);
+            return matrix3D;
+        }
+
+        private void SetMatrix(double m11, double m12, double m13, double m14,
+                               double m21, double m22, double m23, double m24,
+                               double m31, double m32, double m33, double m34,
+                               double offsetX, double offsetY, double offsetZ, double m44)
+        {
+            _m11 = m11;
+            _m12 = m12;
+            _m13 = m13;
+            _m14 = m14;
+            _m21 = m21;
+            _m22 = m22;
+            _m23 = m23;
+            _m24 = m24;
+            _m31 = m31;
+            _m32 = m32;
+            _m33 = m33;
+            _m34 = m34;
+            _offsetX = offsetX;
+            _offsetY = offsetY;
+            _offsetZ = offsetZ;
+            _m44 = m44;
+        }
+
+        private static bool Equals(Matrix3D matrix1, Matrix3D matrix2)
+        {
+            return matrix1.M11.Equals(matrix2.M11) &&
+                   matrix1.M12.Equals(matrix2.M12) &&
+                   matrix1.M13.Equals(matrix2.M13) &&
+                   matrix1.M14.Equals(matrix2.M14) &&
+                   matrix1.M21.Equals(matrix2.M21) &&
+                   matrix1.M22.Equals(matrix2.M22) &&
+                   matrix1.M23.Equals(matrix2.M23) &&
+                   matrix1.M24.Equals(matrix2.M24) &&
+                   matrix1.M31.Equals(matrix2.M31) &&
+                   matrix1.M32.Equals(matrix2.M32) &&
+                   matrix1.M33.Equals(matrix2.M33) &&
+                   matrix1.M34.Equals(matrix2.M34) &&
+                   matrix1.OffsetX.Equals(matrix2.OffsetX) &&
+                   matrix1.OffsetY.Equals(matrix2.OffsetY) &&
+                   matrix1.OffsetZ.Equals(matrix2.OffsetZ) &&
+                   matrix1.M44.Equals(matrix2.M44);
+        }
+
+        private double GetNormalizedAffineDeterminant()
+        {
+            double z20 = _m12 * _m23 - _m22 * _m13;
+            double z10 = _m32 * _m13 - _m12 * _m33;
+            double z00 = _m22 * _m33 - _m32 * _m23;
+
+            return _m31 * z20 + _m21 * z10 + _m11 * z00;
+        }
+
+        private bool IsAffine
+        {
+            get
+            {
+                return (_m14 == 0.0 && _m24 == 0.0 && _m34 == 0.0 && _m44 == 1.0);
+            }
+        }
+
+        private double Determinant
+        {
+            get
+            {
+                if (IsAffine)
+                {
+                    return GetNormalizedAffineDeterminant();
+                }
+
+                // compute all six 2x2 determinants of 2nd two columns
+                double y01 = _m13 * _m24 - _m23 * _m14;
+                double y02 = _m13 * _m34 - _m33 * _m14;
+                double y03 = _m13 * _m44 - _offsetZ * _m14;
+                double y12 = _m23 * _m34 - _m33 * _m24;
+                double y13 = _m23 * _m44 - _offsetZ * _m24;
+                double y23 = _m33 * _m44 - _offsetZ * _m34;
+
+                // Compute 3x3 cofactors for 1st the column
+                double z30 = _m22 * y02 - _m32 * y01 - _m12 * y12;
+                double z20 = _m12 * y13 - _m22 * y03 + _offsetY * y01;
+                double z10 = _m32 * y03 - _offsetY * y02 - _m12 * y23;
+                double z00 = _m22 * y23 - _m32 * y13 + _offsetY * y12;
+
+                return _offsetX * z30 + _m31 * z20 + _m21 * z10 + _m11 * z00;
+            }
+        }
+
+        private static bool IsZero(double value)
+        {
+            return Math.Abs(value) < 10.0 * DBL_EPSILON_RELATIVE_1;
+        }
+
+        private const double DBL_EPSILON_RELATIVE_1 = 1.1102230246251567e-016; /* smallest such that 1.0+DBL_EPSILON != 1.0 */
+
+        private double _m11;
+        private double _m12;
+        private double _m13;
+        private double _m14;
+        private double _m21;
+        private double _m22;
+        private double _m23;
+        private double _m24;
+        private double _m31;
+        private double _m32;
+        private double _m33;
+        private double _m34;
+        private double _offsetX;
+        private double _offsetY;
+        private double _offsetZ;
+        private double _m44;
+    }
+}
+
+namespace ABI.Windows.UI.Xaml.Media.Media3D
+{
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class Matrix3D
+    {
+        public static string GetGuidSignature() => 
+            $"struct(Windows.UI.Xaml.Media.Media3D.Matrix3D;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8;f8)";
+    }
+}
diff --git a/src/cswinrt/strings/additions/Windows.UI.Xaml.Media/Windows.UI.Xaml.Media.cs b/src/cswinrt/strings/additions/Windows.UI.Xaml.Media/Windows.UI.Xaml.Media.cs
new file mode 100644
index 000000000..b156e5104
--- /dev/null
+++ b/src/cswinrt/strings/additions/Windows.UI.Xaml.Media/Windows.UI.Xaml.Media.cs
@@ -0,0 +1,263 @@
+
+namespace Windows.UI.Xaml.Media
+{
+    using global::Windows.Foundation;
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Media.Matrix))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct Matrix : IFormattable
+    {
+        public Matrix(double m11, double m12,
+                      double m21, double m22,
+                      double offsetX, double offsetY)
+        {
+            _m11 = m11;
+            _m12 = m12;
+            _m21 = m21;
+            _m22 = m22;
+            _offsetX = offsetX;
+            _offsetY = offsetY;
+        }
+
+        // the transform is identity by default
+        private static Matrix s_identity = CreateIdentity();
+
+        public double M11
+        {
+            get
+            {
+                return _m11;
+            }
+            set
+            {
+                _m11 = value;
+            }
+        }
+
+        public double M12
+        {
+            get
+            {
+                return _m12;
+            }
+            set
+            {
+                _m12 = value;
+            }
+        }
+
+        public double M21
+        {
+            get
+            {
+                return _m21;
+            }
+            set
+            {
+                _m21 = value;
+            }
+        }
+
+        public double M22
+        {
+            get
+            {
+                return _m22;
+            }
+            set
+            {
+                _m22 = value;
+            }
+        }
+
+        public double OffsetX
+        {
+            get
+            {
+                return _offsetX;
+            }
+            set
+            {
+                _offsetX = value;
+            }
+        }
+
+        public double OffsetY
+        {
+            get
+            {
+                return _offsetY;
+            }
+            set
+            {
+                _offsetY = value;
+            }
+        }
+
+        public static Matrix Identity
+        {
+            get
+            {
+                return s_identity;
+            }
+        }
+
+        public bool IsIdentity
+        {
+            get
+            {
+                return (_m11 == 1 && _m12 == 0 && _m21 == 0 && _m22 == 1 && _offsetX == 0 && _offsetY == 0);
+            }
+        }
+
+        public override string ToString()
+        {
+            // Delegate to the internal method which implements all ToString calls.
+            return ConvertToString(null /* format string */, null /* format provider */);
+        }
+
+        public string ToString(IFormatProvider provider)
+        {
+            // Delegate to the internal method which implements all ToString calls.
+            return ConvertToString(null /* format string */, provider);
+        }
+
+        string IFormattable.ToString(string format, IFormatProvider provider)
+        {
+            // Delegate to the internal method which implements all ToString calls.
+            return ConvertToString(format, provider);
+        }
+
+        private string ConvertToString(string format, IFormatProvider provider)
+        {
+            if (IsIdentity)
+            {
+                return "Identity";
+            }
+
+            // Helper to get the numeric list separator for a given culture.
+            char separator = TokenizerHelper.GetNumericListSeparator(provider);
+            return string.Format(provider,
+                                 "{1:" + format + "}{0}{2:" + format + "}{0}{3:" + format + "}{0}{4:" + format + "}{0}{5:" + format + "}{0}{6:" + format + "}",
+                                 separator,
+                                 _m11,
+                                 _m12,
+                                 _m21,
+                                 _m22,
+                                 _offsetX,
+                                 _offsetY);
+        }
+
+        public Point Transform(Point point)
+        {
+            float x = (float)point.X;
+            float y = (float)point.Y;
+            this.MultiplyPoint(ref x, ref y);
+            Point point2 = new Point(x, y);
+            return point2;
+        }
+
+        public override int GetHashCode()
+        {
+            // Perform field-by-field XOR of HashCodes
+            return M11.GetHashCode() ^
+                   M12.GetHashCode() ^
+                   M21.GetHashCode() ^
+                   M22.GetHashCode() ^
+                   OffsetX.GetHashCode() ^
+                   OffsetY.GetHashCode();
+        }
+
+        public override bool Equals(object o)
+        {
+            return o is Matrix && Matrix.Equals(this, (Matrix)o);
+        }
+
+        public bool Equals(Matrix value)
+        {
+            return Matrix.Equals(this, value);
+        }
+
+        public static bool operator ==(Matrix matrix1, Matrix matrix2)
+        {
+            return matrix1.M11 == matrix2.M11 &&
+                   matrix1.M12 == matrix2.M12 &&
+                   matrix1.M21 == matrix2.M21 &&
+                   matrix1.M22 == matrix2.M22 &&
+                   matrix1.OffsetX == matrix2.OffsetX &&
+                   matrix1.OffsetY == matrix2.OffsetY;
+        }
+
+        public static bool operator !=(Matrix matrix1, Matrix matrix2)
+        {
+            return !(matrix1 == matrix2);
+        }
+
+        private static Matrix CreateIdentity()
+        {
+            Matrix matrix = default;
+            matrix.SetMatrix(1, 0,
+                             0, 1,
+                             0, 0);
+            return matrix;
+        }
+
+        private void SetMatrix(double m11, double m12,
+                               double m21, double m22,
+                               double offsetX, double offsetY)
+        {
+            _m11 = m11;
+            _m12 = m12;
+            _m21 = m21;
+            _m22 = m22;
+            _offsetX = offsetX;
+            _offsetY = offsetY;
+        }
+
+        private void MultiplyPoint(ref float x, ref float y)
+        {
+            double num = (y * _m21) + _offsetX;
+            double num2 = (x * _m12) + _offsetY;
+            x *= (float)_m11;
+            x += (float)num;
+            y *= (float)_m22;
+            y += (float)num2;
+        }
+
+        private static bool Equals(Matrix matrix1, Matrix matrix2)
+        {
+            return matrix1.M11.Equals(matrix2.M11) &&
+                   matrix1.M12.Equals(matrix2.M12) &&
+                   matrix1.M21.Equals(matrix2.M21) &&
+                   matrix1.M22.Equals(matrix2.M22) &&
+                   matrix1.OffsetX.Equals(matrix2.OffsetX) &&
+                   matrix1.OffsetY.Equals(matrix2.OffsetY);
+        }
+
+        private double _m11;
+        private double _m12;
+        private double _m21;
+        private double _m22;
+        private double _offsetX;
+        private double _offsetY;
+    }
+}
+
+namespace ABI.Windows.UI.Xaml.Media
+{
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class Matrix
+    {
+        public static string GetGuidSignature() => $"struct(Windows.UI.Xaml.Media.Matrix;f8;f8;f8;f8;f8;f8)";
+    }
+}
diff --git a/src/cswinrt/strings/additions/Windows.UI.Xaml/Windows.UI.Xaml.SR.cs b/src/cswinrt/strings/additions/Windows.UI.Xaml/Windows.UI.Xaml.SR.cs
new file mode 100644
index 000000000..cbb4596bb
--- /dev/null
+++ b/src/cswinrt/strings/additions/Windows.UI.Xaml/Windows.UI.Xaml.SR.cs
@@ -0,0 +1,17 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Windows.UI.Xaml
+{
+    static class SR
+    {
+        public static string DirectUI_CornerRadius_InvalidMember = "Invalid value for {0} property on CornerRadius.";
+        public static string DirectUI_InvalidArgument = "Invalid argument.";
+        public static string ElementNotAvailable_Default = "The element is not available.";
+        public static string ElementNotEnabled_Default = "The element is not enabled.";
+        public static string XamlParse_Default = "XAML parsing failed.";
+        public static string LayoutCycle_Default = "A cycle occurred while laying out the GUI.";
+        public static string PlatformNotSupported_WindowsRuntime = "Windows Runtime (WinRT) is not supported on this platform.";
+    }
+}
diff --git a/src/cswinrt/strings/additions/Windows.UI.Xaml/Windows.UI.Xaml.cs b/src/cswinrt/strings/additions/Windows.UI.Xaml/Windows.UI.Xaml.cs
new file mode 100644
index 000000000..341d016d6
--- /dev/null
+++ b/src/cswinrt/strings/additions/Windows.UI.Xaml/Windows.UI.Xaml.cs
@@ -0,0 +1,774 @@
+
+namespace Windows.UI.Xaml
+{
+    using global::Windows.Foundation;
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.CornerRadius))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct CornerRadius
+    {
+        private double _TopLeft;
+        private double _TopRight;
+        private double _BottomRight;
+        private double _BottomLeft;
+
+        public CornerRadius(double uniformRadius)
+        {
+            Validate(uniformRadius, uniformRadius, uniformRadius, uniformRadius);
+            _TopLeft = _TopRight = _BottomRight = _BottomLeft = uniformRadius;
+        }
+
+        public CornerRadius(double topLeft, double topRight, double bottomRight, double bottomLeft)
+        {
+            Validate(topLeft, topRight, bottomRight, bottomLeft);
+
+            _TopLeft = topLeft;
+            _TopRight = topRight;
+            _BottomRight = bottomRight;
+            _BottomLeft = bottomLeft;
+        }
+
+        private static void Validate(double topLeft, double topRight, double bottomRight, double bottomLeft)
+        {
+            if (topLeft < 0.0 || double.IsNaN(topLeft))
+                throw new ArgumentException(string.Format(SR.DirectUI_CornerRadius_InvalidMember, "TopLeft"));
+
+            if (topRight < 0.0 || double.IsNaN(topRight))
+                throw new ArgumentException(string.Format(SR.DirectUI_CornerRadius_InvalidMember, "TopRight"));
+
+            if (bottomRight < 0.0 || double.IsNaN(bottomRight))
+                throw new ArgumentException(string.Format(SR.DirectUI_CornerRadius_InvalidMember, "BottomRight"));
+
+            if (bottomLeft < 0.0 || double.IsNaN(bottomLeft))
+                throw new ArgumentException(string.Format(SR.DirectUI_CornerRadius_InvalidMember, "BottomLeft"));
+        }
+
+        public override string ToString()
+        {
+            return ToString(global::System.Globalization.CultureInfo.InvariantCulture);
+        }
+
+        internal string ToString(global::System.Globalization.CultureInfo cultureInfo)
+        {
+            char listSeparator = TokenizerHelper.GetNumericListSeparator(cultureInfo);
+
+            // Initial capacity [64] is an estimate based on a sum of:
+            // 48 = 4x double (twelve digits is generous for the range of values likely)
+            //  8 = 4x Unit Type string (approx two characters)
+            //  4 = 4x separator characters
+            global::System.Text.StringBuilder sb = new global::System.Text.StringBuilder(64);
+
+            sb.Append(InternalToString(_TopLeft, cultureInfo));
+            sb.Append(listSeparator);
+            sb.Append(InternalToString(_TopRight, cultureInfo));
+            sb.Append(listSeparator);
+            sb.Append(InternalToString(_BottomRight, cultureInfo));
+            sb.Append(listSeparator);
+            sb.Append(InternalToString(_BottomLeft, cultureInfo));
+            return sb.ToString();
+        }
+
+        internal string InternalToString(double l, global::System.Globalization.CultureInfo cultureInfo)
+        {
+            if (double.IsNaN(l)) return "Auto";
+            return Convert.ToString(l, cultureInfo);
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is CornerRadius)
+            {
+                CornerRadius otherObj = (CornerRadius)obj;
+                return (this == otherObj);
+            }
+            return (false);
+        }
+
+        public bool Equals(CornerRadius cornerRadius)
+        {
+            return (this == cornerRadius);
+        }
+
+        public override int GetHashCode()
+        {
+            return _TopLeft.GetHashCode() ^ _TopRight.GetHashCode() ^ _BottomLeft.GetHashCode() ^ _BottomRight.GetHashCode();
+        }
+
+        public static bool operator ==(CornerRadius cr1, CornerRadius cr2)
+        {
+            return cr1._TopLeft == cr2._TopLeft && cr1._TopRight == cr2._TopRight && cr1._BottomRight == cr2._BottomRight && cr1._BottomLeft == cr2._BottomLeft;
+        }
+
+        public static bool operator !=(CornerRadius cr1, CornerRadius cr2)
+        {
+            return (!(cr1 == cr2));
+        }
+
+        public double TopLeft
+        {
+            get { return _TopLeft; }
+            set
+            {
+                Validate(value, 0, 0, 0);
+                _TopLeft = value;
+            }
+        }
+
+        public double TopRight
+        {
+            get { return _TopRight; }
+            set
+            {
+                Validate(0, value, 0, 0);
+                _TopRight = value;
+            }
+        }
+
+        public double BottomRight
+        {
+            get { return _BottomRight; }
+            set
+            {
+                Validate(0, 0, value, 0);
+                _BottomRight = value;
+            }
+        }
+
+        public double BottomLeft
+        {
+            get { return _BottomLeft; }
+            set
+            {
+                Validate(0, 0, 0, value);
+                _BottomLeft = value;
+            }
+        }
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    enum GridUnitType
+    {
+        Auto = 0,
+        Pixel,
+        Star,
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.GridLength))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct GridLength
+    {
+        private readonly double _unitValue;
+        private readonly GridUnitType _unitType;
+
+        private const double Default = 1.0;
+        private static readonly GridLength s_auto = new GridLength(Default, GridUnitType.Auto);
+
+        public GridLength(double pixels)
+            : this(pixels, GridUnitType.Pixel)
+        {
+        }
+
+        internal static bool IsFinite(double value)
+        {
+            return !(double.IsNaN(value) || double.IsInfinity(value));
+        }
+
+        public GridLength(double value, GridUnitType type)
+        {
+            if (!IsFinite(value) || value < 0.0)
+            {
+                throw new ArgumentException(SR.DirectUI_InvalidArgument, nameof(value));
+            }
+            if (type != GridUnitType.Auto && type != GridUnitType.Pixel && type != GridUnitType.Star)
+            {
+                throw new ArgumentException(SR.DirectUI_InvalidArgument, nameof(type));
+            }
+
+            _unitValue = (type == GridUnitType.Auto) ? Default : value;
+            _unitType = type;
+        }
+
+
+        public double Value { get { return ((_unitType == GridUnitType.Auto) ? s_auto._unitValue : _unitValue); } }
+        public GridUnitType GridUnitType { get { return (_unitType); } }
+
+
+        public bool IsAbsolute { get { return (_unitType == GridUnitType.Pixel); } }
+        public bool IsAuto { get { return (_unitType == GridUnitType.Auto); } }
+        public bool IsStar { get { return (_unitType == GridUnitType.Star); } }
+
+        public static GridLength Auto
+        {
+            get { return (s_auto); }
+        }
+
+
+        public static bool operator ==(GridLength gl1, GridLength gl2)
+        {
+            return (gl1.GridUnitType == gl2.GridUnitType
+                    && gl1.Value == gl2.Value);
+        }
+
+        public static bool operator !=(GridLength gl1, GridLength gl2)
+        {
+            return (gl1.GridUnitType != gl2.GridUnitType
+                    || gl1.Value != gl2.Value);
+        }
+
+        public override bool Equals(object oCompare)
+        {
+            if (oCompare is GridLength)
+            {
+                GridLength l = (GridLength)oCompare;
+                return (this == l);
+            }
+            else
+                return false;
+        }
+
+        public bool Equals(GridLength gridLength)
+        {
+            return (this == gridLength);
+        }
+
+        public override int GetHashCode()
+        {
+            return ((int)_unitValue + (int)_unitType);
+        }
+
+        public override string ToString()
+        {
+            return this.ToString(global::System.Globalization.CultureInfo.InvariantCulture);
+        }
+
+        internal string ToString(global::System.Globalization.CultureInfo cultureInfo)
+        {
+            char listSeparator = TokenizerHelper.GetNumericListSeparator(cultureInfo);
+
+            // Initial capacity [64] is an estimate based on a sum of:
+            // 12 = 1x double (twelve digits is generous for the range of values likely)
+            //  8 = 4x Unit Type string (approx two characters)
+            //  2 = 2x separator characters
+
+            if (_unitType == GridUnitType.Auto)
+            {
+                return "Auto";
+            }
+            else if (_unitType == GridUnitType.Pixel)
+            {
+                return Convert.ToString(_unitValue, cultureInfo);
+            }
+            else
+            {
+                return Convert.ToString(_unitValue, cultureInfo) + "*";
+            }
+        }
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Thickness))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct Thickness
+    {
+        private double _Left;
+        private double _Top;
+        private double _Right;
+        private double _Bottom;
+
+        public Thickness(double uniformLength)
+        {
+            _Left = _Top = _Right = _Bottom = uniformLength;
+        }
+
+        public Thickness(double left, double top, double right, double bottom)
+        {
+            _Left = left;
+            _Top = top;
+            _Right = right;
+            _Bottom = bottom;
+        }
+
+        public double Left
+        {
+            get { return _Left; }
+            set { _Left = value; }
+        }
+
+        public double Top
+        {
+            get { return _Top; }
+            set { _Top = value; }
+        }
+
+        public double Right
+        {
+            get { return _Right; }
+            set { _Right = value; }
+        }
+
+        public double Bottom
+        {
+            get { return _Bottom; }
+            set { _Bottom = value; }
+        }
+
+        public override string ToString()
+        {
+            return ToString(global::System.Globalization.CultureInfo.InvariantCulture);
+        }
+
+        internal string ToString(global::System.Globalization.CultureInfo cultureInfo)
+        {
+            char listSeparator = TokenizerHelper.GetNumericListSeparator(cultureInfo);
+
+            // Initial capacity [64] is an estimate based on a sum of:
+            // 48 = 4x double (twelve digits is generous for the range of values likely)
+            //  8 = 4x Unit Type string (approx two characters)
+            //  4 = 4x separator characters
+            global::System.Text.StringBuilder sb = new global::System.Text.StringBuilder(64);
+
+            sb.Append(InternalToString(_Left, cultureInfo));
+            sb.Append(listSeparator);
+            sb.Append(InternalToString(_Top, cultureInfo));
+            sb.Append(listSeparator);
+            sb.Append(InternalToString(_Right, cultureInfo));
+            sb.Append(listSeparator);
+            sb.Append(InternalToString(_Bottom, cultureInfo));
+            return sb.ToString();
+        }
+
+        internal string InternalToString(double l, global::System.Globalization.CultureInfo cultureInfo)
+        {
+            if (double.IsNaN(l)) return "Auto";
+            return Convert.ToString(l, cultureInfo);
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is Thickness)
+            {
+                Thickness otherObj = (Thickness)obj;
+                return (this == otherObj);
+            }
+            return (false);
+        }
+
+        public bool Equals(Thickness thickness)
+        {
+            return (this == thickness);
+        }
+
+        public override int GetHashCode()
+        {
+            return _Left.GetHashCode() ^ _Top.GetHashCode() ^ _Right.GetHashCode() ^ _Bottom.GetHashCode();
+        }
+
+        public static bool operator ==(Thickness t1, Thickness t2)
+        {
+            return t1._Left == t2._Left && t1._Top == t2._Top && t1._Right == t2._Right && t1._Bottom == t2._Bottom;
+        }
+
+        public static bool operator !=(Thickness t1, Thickness t2)
+        {
+            return (!(t1 == t2));
+        }
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    enum DurationType
+    {
+        Automatic,
+        TimeSpan,
+        Forever
+    }
+
+    [global::WinRT.WindowsRuntimeType("Windows.UI.Xaml")]
+    [global::WinRT.WindowsRuntimeHelperType(typeof(global::ABI.Windows.UI.Xaml.Duration))]
+    [StructLayout(LayoutKind.Sequential)]
+#if EMBED
+    internal
+#else
+    public
+#endif
+    struct Duration
+    {
+        private readonly TimeSpan _timeSpan;
+        private DurationType _durationType;
+
+        public Duration(TimeSpan timeSpan)
+        {
+            _durationType = DurationType.TimeSpan;
+            _timeSpan = timeSpan;
+        }
+
+        public static implicit operator Duration(TimeSpan timeSpan)
+        {
+            return new Duration(timeSpan);
+        }
+
+        public static Duration operator +(Duration t1, Duration t2)
+        {
+            if (t1.HasTimeSpan && t2.HasTimeSpan)
+            {
+                return new Duration(t1._timeSpan + t2._timeSpan);
+            }
+            else if (t1._durationType != DurationType.Automatic && t2._durationType != DurationType.Automatic)
+            {
+                return Duration.Forever;
+            }
+            else
+            {
+                // Automatic + anything is Automatic
+                return Duration.Automatic;
+            }
+        }
+
+        public static Duration operator -(Duration t1, Duration t2)
+        {
+            if (t1.HasTimeSpan && t2.HasTimeSpan)
+            {
+                return new Duration(t1._timeSpan - t2._timeSpan);
+            }
+            else if (t1._durationType == DurationType.Forever && t2.HasTimeSpan)
+            {
+                return Duration.Forever;
+            }
+            else
+            {
+                return Duration.Automatic;
+            }
+        }
+
+        public static bool operator ==(Duration t1, Duration t2)
+        {
+            return t1.Equals(t2);
+        }
+
+        public static bool operator !=(Duration t1, Duration t2)
+        {
+            return !(t1.Equals(t2));
+        }
+
+        public static bool operator >(Duration t1, Duration t2)
+        {
+            if (t1.HasTimeSpan && t2.HasTimeSpan)
+            {
+                return t1._timeSpan > t2._timeSpan;
+            }
+            else if (t1.HasTimeSpan && t2._durationType == DurationType.Forever)
+            {
+                return false;
+            }
+            else if (t1._durationType == DurationType.Forever && t2.HasTimeSpan)
+            {
+                return true;
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        public static bool operator >=(Duration t1, Duration t2)
+        {
+            if (t1._durationType == DurationType.Automatic && t2._durationType == DurationType.Automatic)
+            {
+                return true;
+            }
+            else if (t1._durationType == DurationType.Automatic || t2._durationType == DurationType.Automatic)
+            {
+                return false;
+            }
+            else
+            {
+                return !(t1 < t2);
+            }
+        }
+
+        public static bool operator <(Duration t1, Duration t2)
+        {
+            if (t1.HasTimeSpan && t2.HasTimeSpan)
+            {
+                return t1._timeSpan < t2._timeSpan;
+            }
+            else if (t1.HasTimeSpan && t2._durationType == DurationType.Forever)
+            {
+                return true;
+            }
+            else if (t1._durationType == DurationType.Forever && t2.HasTimeSpan)
+            {
+                return false;
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        public static bool operator <=(Duration t1, Duration t2)
+        {
+            if (t1._durationType == DurationType.Automatic && t2._durationType == DurationType.Automatic)
+            {
+                return true;
+            }
+            else if (t1._durationType == DurationType.Automatic || t2._durationType == DurationType.Automatic)
+            {
+                return false;
+            }
+            else
+            {
+                return !(t1 > t2);
+            }
+        }
+
+        public static int Compare(Duration t1, Duration t2)
+        {
+            if (t1._durationType == DurationType.Automatic)
+            {
+                if (t2._durationType == DurationType.Automatic)
+                {
+                    return 0;
+                }
+                else
+                {
+                    return -1;
+                }
+            }
+            else if (t2._durationType == DurationType.Automatic)
+            {
+                return 1;
+            }
+            else
+            {
+                if (t1 < t2)
+                {
+                    return -1;
+                }
+                else if (t1 > t2)
+                {
+                    return 1;
+                }
+                else
+                {
+                    return 0;
+                }
+            }
+        }
+
+        public static Duration operator +(Duration duration)
+        {
+            return duration;
+        }
+
+        public bool HasTimeSpan
+        {
+            get
+            {
+                return _durationType == DurationType.TimeSpan;
+            }
+        }
+
+        public static Duration Automatic
+        {
+            get
+            {
+                Duration duration = default;
+                duration._durationType = DurationType.Automatic;
+
+                return duration;
+            }
+        }
+
+        public static Duration Forever
+        {
+            get
+            {
+                Duration duration = default;
+                duration._durationType = DurationType.Forever;
+
+                return duration;
+            }
+        }
+
+        public TimeSpan TimeSpan
+        {
+            get
+            {
+                if (HasTimeSpan)
+                {
+                    return _timeSpan;
+                }
+                else
+                {
+                    throw new InvalidOperationException();
+                }
+            }
+        }
+
+        public Duration Add(Duration duration)
+        {
+            return this + duration;
+        }
+
+        public override bool Equals(object value)
+        {
+            return value is Duration && Equals((Duration)value);
+        }
+
+        public bool Equals(Duration duration)
+        {
+            if (HasTimeSpan)
+            {
+                if (duration.HasTimeSpan)
+                {
+                    return _timeSpan == duration._timeSpan;
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            else
+            {
+                return _durationType == duration._durationType;
+            }
+        }
+
+        public static bool Equals(Duration t1, Duration t2)
+        {
+            return t1.Equals(t2);
+        }
+
+        public override int GetHashCode()
+        {
+            if (HasTimeSpan)
+            {
+                return _timeSpan.GetHashCode();
+            }
+            else
+            {
+                return _durationType.GetHashCode() + 17;
+            }
+        }
+
+        public Duration Subtract(Duration duration)
+        {
+            return this - duration;
+        }
+
+        public override string ToString()
+        {
+            if (HasTimeSpan)
+            {
+                return _timeSpan.ToString(); // "00"; //TypeDescriptor.GetConverter(_timeSpan).ConvertToString(_timeSpan);
+            }
+            else if (_durationType == DurationType.Forever)
+            {
+                return "Forever";
+            }
+            else // IsAutomatic
+            {
+                return "Automatic";
+            }
+        }
+    }
+}
+
+namespace ABI.Windows.UI.Xaml
+{
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class CornerRadius
+    {
+        public static string GetGuidSignature() => $"struct(Windows.UI.Xaml.CornerRadius;f8;f8;f8;f8)";
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class Duration
+    {
+        public static string GetGuidSignature()
+        {
+            string timeSpanSignature = global::WinRT.GuidGenerator.GetSignature(typeof(global::System.TimeSpan));
+            string durationTypeSignature = global::WinRT.GuidGenerator.GetSignature(typeof(global::Windows.UI.Xaml.DurationType));
+            return $"struct(Windows.UI.Xaml.Duration;{timeSpanSignature};{durationTypeSignature})";
+        }
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class DurationType
+    {
+        public static string GetGuidSignature() => "enum(Windows.UI.Xaml.DurationType;i4)";
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class GridLength
+    {
+        public static string GetGuidSignature()
+        {
+            string unitTypeSignature = global::WinRT.GuidGenerator.GetSignature(typeof(global::Windows.UI.Xaml.GridUnitType));
+            return $"struct(Windows.UI.Xaml.GridLength;f8;{unitTypeSignature})";
+        }
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class GridUnitType
+    {
+        public static string GetGuidSignature() => "enum(Windows.UI.Xaml.GridUnitType;i4)";
+    }
+
+#if EMBED
+    internal
+#else
+    public
+#endif
+    static class Thickness
+    {
+        public static string GetGuidSignature() => $"struct(Windows.UI.Xaml.Thickness;f8;f8;f8;f8)";
+    }
+}