diff --git a/lib/smartystreets_ruby_sdk/us_enrichment/geo_reference/lookup.rb b/lib/smartystreets_ruby_sdk/us_enrichment/geo_reference/lookup.rb
index 732feac..2cfb1e7 100644
--- a/lib/smartystreets_ruby_sdk/us_enrichment/geo_reference/lookup.rb
+++ b/lib/smartystreets_ruby_sdk/us_enrichment/geo_reference/lookup.rb
@@ -2,13 +2,18 @@ module SmartyStreets
   module USEnrichment
     module GeoReference
       class Lookup
-        attr_reader :smarty_key, :data_set, :data_sub_set, :etag
+        attr_reader :smarty_key, :data_set, :data_sub_set, :etag, :custom_param_hash
 
-        def initialize(smarty_key, etag=nil)
+        def initialize(smarty_key, etag=nil, custom_param_hash=nil)
           @smarty_key = smarty_key
           @data_set = 'geo-reference'
           @data_sub_set = nil
           @etag = etag
+          @custom_param_hash = {}
+        end
+
+        def add_custom_parameter(parameter, value)
+          @custom_param_hash[parameter] = value
         end
       end
     end
diff --git a/lib/smartystreets_ruby_sdk/us_enrichment/property/financial/lookup.rb b/lib/smartystreets_ruby_sdk/us_enrichment/property/financial/lookup.rb
index 3c2e728..a965c5d 100644
--- a/lib/smartystreets_ruby_sdk/us_enrichment/property/financial/lookup.rb
+++ b/lib/smartystreets_ruby_sdk/us_enrichment/property/financial/lookup.rb
@@ -3,13 +3,18 @@ module USEnrichment
         module Property
             module Financial
                 class Lookup
-                    attr_reader :smarty_key, :data_set, :data_sub_set, :etag
+                    attr_reader :smarty_key, :data_set, :data_sub_set, :etag, :custom_param_hash
                     
-                    def initialize(smarty_key, etag=nil)
+                    def initialize(smarty_key, etag=nil, custom_param_hash=nil)
                         @smarty_key = smarty_key
                         @data_set = "property"
                         @data_sub_set = "financial"
                         @etag = etag
+                        @custom_param_hash = {}
+                    end
+
+                    def add_custom_parameter(parameter, value)
+                        @custom_param_hash[parameter] = value
                     end
                 end
             end
diff --git a/lib/smartystreets_ruby_sdk/us_enrichment/property/principal/lookup.rb b/lib/smartystreets_ruby_sdk/us_enrichment/property/principal/lookup.rb
index c851470..812ab7f 100644
--- a/lib/smartystreets_ruby_sdk/us_enrichment/property/principal/lookup.rb
+++ b/lib/smartystreets_ruby_sdk/us_enrichment/property/principal/lookup.rb
@@ -3,13 +3,18 @@ module USEnrichment
         module Property
             module Principal
                 class Lookup
-                    attr_reader :smarty_key, :data_set, :data_sub_set, :etag
+                    attr_reader :smarty_key, :data_set, :data_sub_set, :etag, :custom_param_hash
                     
-                    def initialize(smarty_key, etag=nil)
+                    def initialize(smarty_key, etag=nil, custom_param_hash=nil)
                         @smarty_key = smarty_key
                         @data_set = "property"
                         @data_sub_set = "principal"
                         @etag = etag
+                        @custom_param_hash = {}
+                    end
+
+                    def add_custom_parameter(parameter, value)
+                        @custom_param_hash[parameter] = value
                     end
                 end
             end
diff --git a/lib/smartystreets_ruby_sdk/us_enrichment/secondary/count/lookup.rb b/lib/smartystreets_ruby_sdk/us_enrichment/secondary/count/lookup.rb
index 4fe88c8..e0d78da 100644
--- a/lib/smartystreets_ruby_sdk/us_enrichment/secondary/count/lookup.rb
+++ b/lib/smartystreets_ruby_sdk/us_enrichment/secondary/count/lookup.rb
@@ -3,13 +3,18 @@ module USEnrichment
     module Secondary
       module Count
         class Lookup
-          attr_reader :smarty_key, :data_set, :data_sub_set, :etag
+          attr_reader :smarty_key, :data_set, :data_sub_set, :etag, :custom_param_hash
               
-          def initialize(smarty_key, etag=nil)
+          def initialize(smarty_key, etag=nil, custom_param_hash=nil)
             @smarty_key = smarty_key
             @data_set = "secondary"
             @data_sub_set = "count"
             @etag = etag
+            @custom_param_hash = {}
+          end
+
+          def add_custom_parameter(parameter, value)
+            @custom_param_hash[parameter] = value
           end
         end
       end
diff --git a/lib/smartystreets_ruby_sdk/us_enrichment/secondary/lookup.rb b/lib/smartystreets_ruby_sdk/us_enrichment/secondary/lookup.rb
index 48e8e1e..4829cb7 100644
--- a/lib/smartystreets_ruby_sdk/us_enrichment/secondary/lookup.rb
+++ b/lib/smartystreets_ruby_sdk/us_enrichment/secondary/lookup.rb
@@ -2,13 +2,18 @@ module SmartyStreets
   module USEnrichment
     module Secondary
       class Lookup
-        attr_reader :smarty_key, :data_set, :data_sub_set, :etag
+        attr_reader :smarty_key, :data_set, :data_sub_set, :etag, :custom_param_hash
               
-        def initialize(smarty_key, etag=nil)
+        def initialize(smarty_key, etag=nil, custom_param_hash=nil)
           @smarty_key = smarty_key
           @data_set = "secondary"
           @data_sub_set = nil
           @etag = etag
+          @custom_param_hash = {}
+        end
+
+        def add_custom_parameter(parameter, value)
+          @custom_param_hash[parameter] = value
         end
       end
     end
diff --git a/test/smartystreets_ruby_sdk/us_street/test_street_client.rb b/test/smartystreets_ruby_sdk/us_street/test_street_client.rb
index f5f719d..105defd 100644
--- a/test/smartystreets_ruby_sdk/us_street/test_street_client.rb
+++ b/test/smartystreets_ruby_sdk/us_street/test_street_client.rb
@@ -40,6 +40,8 @@ def test_send_populated_lookup
         'match' => SmartyStreets::USStreet::MatchType::ENHANCED,
         'candidates' => 5,
         'format' => SmartyStreets::USStreet::OutputFormat::PROJECT_USA,
+        'county_source' => SmartyStreets::USStreet::CountySource::GEOGRAPHIC,
+        'parameter' => 'value',
     }
     serializer = FakeSerializer.new(expected_parameters)
     client = Client.new(sender, serializer)
@@ -56,6 +58,8 @@ def test_send_populated_lookup
     lookup.urbanization = '10'
     lookup.match = SmartyStreets::USStreet::MatchType::ENHANCED
     lookup.format = SmartyStreets::USStreet::OutputFormat::PROJECT_USA
+    lookup.county_source = SmartyStreets::USStreet::CountySource::GEOGRAPHIC
+    lookup.add_custom_parameter('parameter', 'value')
     client.send_lookup(lookup)
 
     assert_equal(expected_parameters, sender.request.parameters)