diff --git a/lib/directive/ng_control.dart b/lib/directive/ng_control.dart
index 70d065b62..155b79582 100644
--- a/lib/directive/ng_control.dart
+++ b/lib/directive/ng_control.dart
@@ -170,18 +170,23 @@ abstract class NgControl implements NgAttachAware, NgDetachAware {
    * error is real).
    */
   updateControlValidity(NgControl ngModel, String errorType, bool isValid) {
+    String validClassName = errorType + '-valid';
+    String invalidClassName = errorType + '-invalid';
+
     if (isValid) {
       if (errors.containsKey(errorType)) {
         Set errorsByName = errors[errorType];
         errorsByName.remove(ngModel);
         if (errorsByName.isEmpty) {
           errors.remove(errorType);
+          element..removeClass(invalidClassName)..addClass(validClassName);
         }
       }
       if (errors.isEmpty) {
         valid = true;
       }
     } else {
+      element..removeClass(validClassName)..addClass(invalidClassName);
       errors.putIfAbsent(errorType, () => new Set()).add(ngModel);
       invalid = true;
     }
diff --git a/test/directive/ng_form_spec.dart b/test/directive/ng_form_spec.dart
index 6b4d8acff..6780ecf3b 100644
--- a/test/directive/ng_form_spec.dart
+++ b/test/directive/ng_form_spec.dart
@@ -529,6 +529,53 @@ void main() {
       }));
     });
 
+    describe('validators', () {
+      it('should display the valid and invalid CSS classes on the element for each validation',     
+        inject((TestBed _, Scope scope) {
+
+        var form = _.compile(
+          '<form name="myForm">' +
+          ' <input type="text" ng-model="myModel" required />' +
+          '</form>'
+        );
+
+        scope.apply();
+
+        expect(form.classes.contains('ng-required-invalid')).toBe(true);
+        expect(form.classes.contains('ng-required-valid')).toBe(false);
+
+        scope.apply(() {
+          scope.context['myModel'] = 'value'; 
+        });
+
+        expect(form.classes.contains('ng-required-valid')).toBe(true);
+        expect(form.classes.contains('ng-required-invalid')).toBe(false);
+      }));
+
+      it('should display the valid and invalid CSS classes on the element for custom validations', () {
+        module((Module module) {
+          module.type(MyCustomFormValidator);
+        });
+        inject((TestBed _, Scope scope) {
+          var form = _.compile('<form name="myForm">' +
+                               ' <input type="text" ng-model="myModel" custom-form-validation />' +
+                               '</form>');
+
+          scope.apply();
+
+          expect(form.classes.contains('custom-invalid')).toBe(true);
+          expect(form.classes.contains('custom-valid')).toBe(false);
+
+          scope.apply(() {
+            scope.context['myModel'] = 'yes'; 
+          });
+
+          expect(form.classes.contains('custom-valid')).toBe(true);
+          expect(form.classes.contains('custom-invalid')).toBe(false);
+        });
+      });
+    });
+
     describe('reset()', () {
       it('should reset the model value to its original state', inject((TestBed _) {
         _.compile('<form name="superForm">' +
@@ -661,3 +708,17 @@ void main() {
     });
   });
 }
+
+@NgDirective(
+    selector: '[custom-form-validation]')
+class MyCustomFormValidator extends NgValidator {
+  MyCustomFormValidator(NgModel ngModel) {
+    ngModel.addValidator(this);
+  }
+
+  final String name = 'custom';
+
+  bool isValid(name) {
+    return name != null && name == 'yes';
+  }
+}
diff --git a/test/directive/ng_model_spec.dart b/test/directive/ng_model_spec.dart
index 45a93fec2..750d4ee9e 100644
--- a/test/directive/ng_model_spec.dart
+++ b/test/directive/ng_model_spec.dart
@@ -8,7 +8,8 @@ void main() {
     TestBed _;
 
     beforeEach(module((Module module) {
-      module..type(ControllerWithNoLove);
+      module.type(ControllerWithNoLove);
+      module.type(MyCustomInputValidator);
     }));
 
     beforeEach(inject((TestBed tb) => _ = tb));
@@ -1307,6 +1308,46 @@ void main() {
       expect(model.untouched).toBe(true);
     });
 
+    describe('validators', () {
+      it('should display the valid and invalid CSS classes on the element for each validation',     
+        inject((TestBed _, Scope scope) {
+
+        var input = _.compile('<input type="email" ng-model="myModel" />');
+
+        scope.apply(() {
+          scope.context['myModel'] = 'value'; 
+        });
+
+        expect(input.classes.contains('ng-email-invalid')).toBe(true);
+        expect(input.classes.contains('ng-email-valid')).toBe(false);
+
+        scope.apply(() {
+          scope.context['myModel'] = 'value@email.com'; 
+        });
+
+        expect(input.classes.contains('ng-email-valid')).toBe(true);
+        expect(input.classes.contains('ng-email-invalid')).toBe(false);
+      }));
+
+      it('should display the valid and invalid CSS classes on the element for custom validations',
+        inject((TestBed _, Scope scope) {
+
+        var input = _.compile('<input type="text" ng-model="myModel" custom-input-validation />');
+
+        scope.apply();
+
+        expect(input.classes.contains('custom-invalid')).toBe(true);
+        expect(input.classes.contains('custom-valid')).toBe(false);
+
+        scope.apply(() {
+          scope.context['myModel'] = 'yes'; 
+        });
+
+        expect(input.classes.contains('custom-valid')).toBe(true);
+        expect(input.classes.contains('custom-invalid')).toBe(false);
+      }));
+    });
+
     describe('converters', () {
       it('should parse the model value according to the given parser', inject((Scope scope) {
         _.compile('<input type="text" ng-model="model" probe="i">');
@@ -1439,3 +1480,17 @@ class VowelValueParser implements NgModelConverter {
     return value;
   }
 }
+
+@NgDirective(
+    selector: '[custom-input-validation]')
+class MyCustomInputValidator extends NgValidator {
+  MyCustomInputValidator(NgModel ngModel) {
+    ngModel.addValidator(this);
+  }
+
+  final String name = 'custom';
+
+  bool isValid(name) {
+    return name != null && name == 'yes';
+  }
+}