diff --git a/modules/angular2/src/core/facade/promise.dart b/modules/angular2/src/core/facade/promise.dart
index 53920b2e17..f8a6c3f617 100644
--- a/modules/angular2/src/core/facade/promise.dart
+++ b/modules/angular2/src/core/facade/promise.dart
@@ -1,6 +1,7 @@
 library angular2.core.facade.promise;
 
 import 'dart:async';
+import 'dart:async' as async;
 export 'dart:async' show Future;
 
 class PromiseWrapper {
@@ -29,6 +30,10 @@ class PromiseWrapper {
     return promise.catchError(onError);
   }
 
+  static void scheduleMicrotask(fn) {
+    async.scheduleMicrotask(fn);
+  }
+
   static PromiseCompleter<dynamic> completer() =>
       new PromiseCompleter(new Completer());
 }
diff --git a/modules/angular2/src/core/facade/promise.ts b/modules/angular2/src/core/facade/promise.ts
index 1fcd901b8d..27bbc41a7f 100644
--- a/modules/angular2/src/core/facade/promise.ts
+++ b/modules/angular2/src/core/facade/promise.ts
@@ -40,6 +40,10 @@ export class PromiseWrapper {
     });
   }
 
+  static scheduleMicrotask(computation: () => any): void {
+    PromiseWrapper.then(PromiseWrapper.resolve(null), computation, (_) => {});
+  }
+
   static completer(): PromiseCompleter<any> {
     var resolve;
     var reject;
diff --git a/modules/angular2/src/core/forms/directives/ng_form.ts b/modules/angular2/src/core/forms/directives/ng_form.ts
index 3ba5d5a74a..3c23e3d7d4 100644
--- a/modules/angular2/src/core/forms/directives/ng_form.ts
+++ b/modules/angular2/src/core/forms/directives/ng_form.ts
@@ -105,7 +105,7 @@ export class NgForm extends ControlContainer implements Form {
   get controls(): {[key: string]: AbstractControl} { return this.form.controls; }
 
   addControl(dir: NgControl): void {
-    this._later(_ => {
+    PromiseWrapper.scheduleMicrotask(() => {
       var container = this._findContainer(dir.path);
       var ctrl = new Control();
       setUpControl(ctrl, dir);
@@ -117,7 +117,7 @@ export class NgForm extends ControlContainer implements Form {
   getControl(dir: NgControl): Control { return <Control>this.form.find(dir.path); }
 
   removeControl(dir: NgControl): void {
-    this._later(_ => {
+    PromiseWrapper.scheduleMicrotask(() => {
       var container = this._findContainer(dir.path);
       if (isPresent(container)) {
         container.removeControl(dir.name);
@@ -127,7 +127,7 @@ export class NgForm extends ControlContainer implements Form {
   }
 
   addControlGroup(dir: NgControlGroup): void {
-    this._later(_ => {
+    PromiseWrapper.scheduleMicrotask(() => {
       var container = this._findContainer(dir.path);
       var group = new ControlGroup({});
       setUpControlGroup(group, dir);
@@ -137,7 +137,7 @@ export class NgForm extends ControlContainer implements Form {
   }
 
   removeControlGroup(dir: NgControlGroup): void {
-    this._later(_ => {
+    PromiseWrapper.scheduleMicrotask(() => {
       var container = this._findContainer(dir.path);
       if (isPresent(container)) {
         container.removeControl(dir.name);
@@ -151,7 +151,7 @@ export class NgForm extends ControlContainer implements Form {
   }
 
   updateModel(dir: NgControl, value: any): void {
-    this._later(_ => {
+    PromiseWrapper.scheduleMicrotask(() => {
       var ctrl = <Control>this.form.find(dir.path);
       ctrl.updateValue(value);
     });
@@ -167,7 +167,4 @@ export class NgForm extends ControlContainer implements Form {
     path.pop();
     return ListWrapper.isEmpty(path) ? this.form : <ControlGroup>this.form.find(path);
   }
-
-  /** @internal */
-  _later(fn): void { PromiseWrapper.then(PromiseWrapper.resolve(null), fn, (_) => {}); }
 }
diff --git a/modules/angular2/src/core/forms/model.ts b/modules/angular2/src/core/forms/model.ts
index b6ea86531c..d952ff73ef 100644
--- a/modules/angular2/src/core/forms/model.ts
+++ b/modules/angular2/src/core/forms/model.ts
@@ -59,8 +59,9 @@ export abstract class AbstractControl {
   private _pristine: boolean = true;
   private _touched: boolean = false;
   private _parent: ControlGroup | ControlArray;
+  private _asyncValidationSubscription;
 
-  constructor(public validator: Function) {}
+  constructor(public validator: Function, public asyncValidator: Function) {}
 
   get value(): any { return this._value; }
 
@@ -119,10 +120,14 @@ export abstract class AbstractControl {
 
     this._updateValue();
 
-    this._errors = this.validator(this);
+    this._errors = this._runValidator();
     this._controlsErrors = this._calculateControlsErrors();
     this._status = this._calculateStatus();
 
+    if (this._status == VALID || this._status == PENDING) {
+      this._runAsyncValidator();
+    }
+
     if (emitEvent) {
       ObservableWrapper.callNext(this._valueChanges, this._value);
     }
@@ -132,6 +137,23 @@ export abstract class AbstractControl {
     }
   }
 
+  private _runValidator() { return isPresent(this.validator) ? this.validator(this) : null; }
+
+  private _runAsyncValidator() {
+    if (isPresent(this.asyncValidator)) {
+      this._status = PENDING;
+      this._cancelExistingSubscription();
+      this._asyncValidationSubscription =
+          ObservableWrapper.subscribe(this.asyncValidator(this), res => this.setErrors(res));
+    }
+  }
+
+  private _cancelExistingSubscription(): void {
+    if (isPresent(this._asyncValidationSubscription)) {
+      ObservableWrapper.dispose(this._asyncValidationSubscription);
+    }
+  }
+
   /**
    * Sets errors on a control.
    *
@@ -190,13 +212,18 @@ export abstract class AbstractControl {
   }
 
   private _calculateStatus(): string {
-    return isPresent(this._errors) || isPresent(this._controlsErrors) ? INVALID : VALID;
+    if (isPresent(this._errors)) return INVALID;
+    if (this._anyControlsHaveStatus(PENDING)) return PENDING;
+    if (this._anyControlsHaveStatus(INVALID)) return INVALID;
+    return VALID;
   }
 
   /** @internal */
   abstract _updateValue(): void;
   /** @internal */
   abstract _calculateControlsErrors(): any;
+  /** @internal */
+  abstract _anyControlsHaveStatus(status: string): boolean;
 }
 
 /**
@@ -219,8 +246,8 @@ export class Control extends AbstractControl {
   /** @internal */
   _onChange: Function;
 
-  constructor(value: any = null, validator: Function = Validators.nullValidator) {
-    super(validator);
+  constructor(value: any = null, validator: Function = null, asyncValidator: Function = null) {
+    super(validator, asyncValidator);
     this._value = value;
     this.updateValueAndValidity({onlySelf: true, emitEvent: false});
     this._valueChanges = new EventEmitter();
@@ -259,6 +286,11 @@ export class Control extends AbstractControl {
    */
   _calculateControlsErrors() { return null; }
 
+  /**
+   * @internal
+   */
+  _anyControlsHaveStatus(status: string): boolean { return false; }
+
   /**
    * Register a listener for change events.
    */
@@ -282,9 +314,9 @@ export class ControlGroup extends AbstractControl {
   private _optionals: {[key: string]: boolean};
 
   constructor(public controls: {[key: string]: AbstractControl},
-              optionals: {[key: string]: boolean} = null,
-              validator: Function = Validators.nullValidator) {
-    super(validator);
+              optionals: {[key: string]: boolean} = null, validator: Function = null,
+              asyncValidator: Function = null) {
+    super(validator, asyncValidator);
     this._optionals = isPresent(optionals) ? optionals : {};
     this._valueChanges = new EventEmitter();
 
@@ -348,6 +380,15 @@ export class ControlGroup extends AbstractControl {
     return StringMapWrapper.isEmpty(res) ? null : res;
   }
 
+  /** @internal */
+  _anyControlsHaveStatus(status: string): boolean {
+    var res = false;
+    StringMapWrapper.forEach(this.controls, (control, name) => {
+      res = res || (this.contains(name) && control.status == status);
+    });
+    return res;
+  }
+
   /** @internal */
   _reduceValue() {
     return this._reduceChildren({}, (acc, control, name) => {
@@ -396,8 +437,9 @@ export class ControlGroup extends AbstractControl {
  * ### Example ([live demo](http://plnkr.co/edit/23DESOpbNnBpBHZt1BR4?p=preview))
  */
 export class ControlArray extends AbstractControl {
-  constructor(public controls: AbstractControl[], validator: Function = Validators.nullValidator) {
-    super(validator);
+  constructor(public controls: AbstractControl[], validator: Function = null,
+              asyncValidator: Function = null) {
+    super(validator, asyncValidator);
 
     this._valueChanges = new EventEmitter();
 
@@ -457,6 +499,12 @@ export class ControlArray extends AbstractControl {
     return anyErrors ? res : null;
   }
 
+  /** @internal */
+  _anyControlsHaveStatus(status: string): boolean {
+    return ListWrapper.any(this.controls, c => c.status == status);
+  }
+
+
   /** @internal */
   _setParentForControls(): void {
     this.controls.forEach((control) => { control.setParent(this); });
diff --git a/modules/angular2/test/core/forms/form_builder_spec.ts b/modules/angular2/test/core/forms/form_builder_spec.ts
index 5e061fa7c1..d9874a2cf2 100644
--- a/modules/angular2/test/core/forms/form_builder_spec.ts
+++ b/modules/angular2/test/core/forms/form_builder_spec.ts
@@ -50,12 +50,6 @@ export function main() {
       expect(g.validator).toBe(Validators.nullValidator);
     });
 
-    it("should use default validators when no validators are provided", () => {
-      var g = b.group({"login": "some value"});
-      expect(g.controls["login"].validator).toBe(Validators.nullValidator);
-      expect(g.validator).toBe(Validators.nullValidator);
-    });
-
     it("should create control arrays", () => {
       var c = b.control("three");
       var a = b.array(["one", ["two", Validators.required], c, b.array(['four'])]);
diff --git a/modules/angular2/test/core/forms/integration_spec.ts b/modules/angular2/test/core/forms/integration_spec.ts
index 533fa3a3af..fa5efb136e 100644
--- a/modules/angular2/test/core/forms/integration_spec.ts
+++ b/modules/angular2/test/core/forms/integration_spec.ts
@@ -38,6 +38,7 @@ import {By} from 'angular2/src/core/debug';
 import {ListWrapper} from 'angular2/src/core/facade/collection';
 import {ObservableWrapper} from 'angular2/src/core/facade/async';
 import {CONST_EXPR} from 'angular2/src/core/facade/lang';
+import {PromiseWrapper} from "angular2/src/core/facade/promise";
 
 export function main() {
   describe("integration tests", () => {
@@ -445,7 +446,7 @@ export function main() {
            });
          }));
 
-      it("should use validators defined in the model",
+      it("should use sync validators defined in the model",
          inject([TestComponentBuilder, AsyncTestCompleter], (tcb: TestComponentBuilder, async) => {
            var form = new ControlGroup({"login": new Control("aa", Validators.required)});
 
@@ -467,6 +468,41 @@ export function main() {
              async.done();
            });
          }));
+
+      it("should use async validators defined in the model",
+         inject([TestComponentBuilder], fakeAsync((tcb: TestComponentBuilder) => {
+                  var control =
+                      new Control("", Validators.required, uniqLoginAsyncValidator("expected"));
+                  var form = new ControlGroup({"login": control});
+
+                  var t = `<div [ng-form-model]="form">
+                  <input type="text" ng-control="login">
+                 </div>`;
+
+                  var rootTC;
+                  tcb.overrideTemplate(MyComp, t).createAsync(MyComp).then((root) => rootTC = root);
+                  tick();
+
+                  rootTC.debugElement.componentInstance.form = form;
+                  rootTC.detectChanges();
+
+                  expect(form.hasError("required", ["login"])).toEqual(true);
+
+                  var input = rootTC.debugElement.query(By.css("input"));
+                  input.nativeElement.value = "wrong value";
+                  dispatchEvent(input.nativeElement, "change");
+
+                  expect(form.pending).toEqual(true);
+                  tick();
+
+                  expect(form.hasError("uniqLogin", ["login"])).toEqual(true);
+
+                  input.nativeElement.value = "expected";
+                  dispatchEvent(input.nativeElement, "change");
+                  tick();
+
+                  expect(form.valid).toEqual(true);
+                })));
     });
 
     describe("nested forms", () => {
@@ -923,6 +959,15 @@ class MyInput implements ControlValueAccessor {
   }
 }
 
+function uniqLoginAsyncValidator(expectedValue: string) {
+  return (c) => {
+    var e = new EventEmitter();
+    var res = (c.value == expectedValue) ? null : {"uniqLogin": true};
+    PromiseWrapper.scheduleMicrotask(() => ObservableWrapper.callNext(e, res));
+    return e;
+  };
+}
+
 function loginIsEmptyGroupValidator(c: ControlGroup) {
   return c.controls["login"].value == "" ? {"loginIsEmpty": true} : null;
 }
diff --git a/modules/angular2/test/core/forms/model_spec.ts b/modules/angular2/test/core/forms/model_spec.ts
index dee17c62fc..a070e8b4b4 100644
--- a/modules/angular2/test/core/forms/model_spec.ts
+++ b/modules/angular2/test/core/forms/model_spec.ts
@@ -14,16 +14,32 @@ import {
   inject
 } from 'angular2/testing_internal';
 import {ControlGroup, Control, ControlArray, Validators} from 'angular2/core';
-import {ObservableWrapper} from 'angular2/src/core/facade/async';
+import {isPresent, CONST_EXPR} from 'angular2/src/core/facade/lang';
+import {EventEmitter, TimerWrapper, ObservableWrapper} from 'angular2/src/core/facade/async';
 import {IS_DART} from '../../platform';
+import {PromiseWrapper} from "angular2/src/core/facade/promise";
 
 export function main() {
+  function asyncValidator(expected, timeouts = CONST_EXPR({})) {
+    return (c) => {
+      var e = new EventEmitter();
+      var t = isPresent(timeouts[c.value]) ? timeouts[c.value] : 0;
+      var res = c.value != expected ? {"async": true} : null;
+
+      if (t == 0) {
+        PromiseWrapper.scheduleMicrotask(() => { ObservableWrapper.callNext(e, res); });
+      } else {
+        TimerWrapper.setTimeout(() => { ObservableWrapper.callNext(e, res); }, t);
+      }
+      return e;
+    };
+  }
+
   describe("Form Model", () => {
     describe("Control", () => {
       it("should default the value to null", () => {
         var c = new Control();
         expect(c.value).toBe(null);
-        expect(c.validator).toBe(Validators.nullValidator);
       });
 
       describe("validator", () => {
@@ -44,6 +60,60 @@ export function main() {
         });
       });
 
+      describe("asyncValidator", () => {
+        it("should run validator with the initial value", fakeAsync(() => {
+             var c = new Control("value", null, asyncValidator("expected"));
+             tick();
+
+             expect(c.valid).toEqual(false);
+             expect(c.errors).toEqual({"async": true});
+           }));
+
+        it("should rerun the validator when the value changes", fakeAsync(() => {
+             var c = new Control("value", null, asyncValidator("expected"));
+
+             c.updateValue("expected");
+             tick();
+
+             expect(c.valid).toEqual(true);
+           }));
+
+        it("should run the async validator only when the sync validator passes", fakeAsync(() => {
+             var c = new Control("", Validators.required, asyncValidator("expected"));
+             tick();
+
+             expect(c.errors).toEqual({"required": true});
+
+             c.updateValue("some value");
+             tick();
+
+             expect(c.errors).toEqual({"async": true});
+           }));
+
+        it("should mark the control as pending while running the async validation",
+           fakeAsync(() => {
+             var c = new Control("", null, asyncValidator("expected"));
+
+             expect(c.pending).toEqual(true);
+
+             tick();
+
+             expect(c.pending).toEqual(false);
+           }));
+
+        it("should only use the latest async validation run", fakeAsync(() => {
+             var c =
+                 new Control("", null, asyncValidator("expected", {"long": 200, "expected": 100}));
+
+             c.updateValue("long");
+             c.updateValue("expected");
+
+             tick(300);
+
+             expect(c.valid).toEqual(true);
+           }));
+      });
+
       describe("dirty", () => {
         it("should be false after creating a control", () => {
           var c = new Control("value");
@@ -154,7 +224,7 @@ export function main() {
 
       describe("setErrors", () => {
         it("should set errors on a control", () => {
-          var c = new Control("someValue", Validators.nullValidator);
+          var c = new Control("someValue");
 
           c.setErrors({"someError": true});
 
@@ -456,6 +526,42 @@ export function main() {
           expect(g.getError("required", ["invalid"])).toEqual(null);
         });
       });
+
+      describe("asyncValidator", () => {
+        it("should run the async validator", fakeAsync(() => {
+             var c = new Control("value");
+             var g = new ControlGroup({"one": c}, null, null, asyncValidator("expected"));
+
+             expect(g.pending).toEqual(true);
+
+             tick(1);
+
+             expect(g.errors).toEqual({"async": true});
+             expect(g.pending).toEqual(false);
+           }));
+
+        it("should set the parent group's status to pending", fakeAsync(() => {
+             var c = new Control("value", null, asyncValidator("expected"));
+             var g = new ControlGroup({"one": c});
+
+             expect(g.pending).toEqual(true);
+
+             tick(1);
+
+             expect(g.pending).toEqual(false);
+           }));
+
+        it("should run the parent group's async validator when children are pending",
+           fakeAsync(() => {
+             var c = new Control("value", null, asyncValidator("expected"));
+             var g = new ControlGroup({"one": c}, null, null, asyncValidator("expected"));
+
+             tick(1);
+
+             expect(g.errors).toEqual({"async": true});
+             expect(g.find(["one"]).errors).toEqual({"async": true});
+           }));
+      })
     });
 
     describe("ControlArray", () => {
@@ -697,6 +803,20 @@ export function main() {
           expect(g.find(["array", 0]).value).toEqual("111");
         });
       });
+
+      describe("asyncValidator", () => {
+        it("should run the async validator", fakeAsync(() => {
+             var c = new Control("value");
+             var g = new ControlArray([c], null, asyncValidator("expected"));
+
+             expect(g.pending).toEqual(true);
+
+             tick(1);
+
+             expect(g.errors).toEqual({"async": true});
+             expect(g.pending).toEqual(false);
+           }));
+      })
     });
   });
 }
diff --git a/modules/angular2/test/public_api_spec.ts b/modules/angular2/test/public_api_spec.ts
index 58f0062369..703b47fbf9 100644
--- a/modules/angular2/test/public_api_spec.ts
+++ b/modules/angular2/test/public_api_spec.ts
@@ -61,6 +61,8 @@ var NG_API = [
   'AbstractControl.valid',
   'AbstractControl.validator',
   'AbstractControl.validator=',
+  'AbstractControl.asyncValidator',
+  'AbstractControl.asyncValidator=',
   'AbstractControl.value',
   'AbstractControl.valueChanges',
   'AbstractControlDirective',
@@ -299,6 +301,8 @@ var NG_API = [
   'Control.valid',
   'Control.validator',
   'Control.validator=',
+  'Control.asyncValidator',
+  'Control.asyncValidator=',
   'Control.value',
   'Control.valueChanges',
   'Control.setErrors()',
@@ -329,6 +333,8 @@ var NG_API = [
   'ControlArray.valid',
   'ControlArray.validator',
   'ControlArray.validator=',
+  'ControlArray.asyncValidator',
+  'ControlArray.asyncValidator=',
   'ControlArray.value',
   'ControlArray.valueChanges',
   'ControlArray.setErrors()',
@@ -373,6 +379,8 @@ var NG_API = [
   'ControlGroup.valid',
   'ControlGroup.validator',
   'ControlGroup.validator=',
+  'ControlGroup.asyncValidator',
+  'ControlGroup.asyncValidator=',
   'ControlGroup.value',
   'ControlGroup.valueChanges',
   'ControlGroup.setErrors()',