diff --git a/lib/validatable.js b/lib/validatable.js
index 53dac713..6d0b8ee5 100644
--- a/lib/validatable.js
+++ b/lib/validatable.js
@@ -11,6 +11,8 @@ Validatable.validatesInclusionOf = getConfigurator('inclusion');
 Validatable.validatesExclusionOf = getConfigurator('exclusion');
 Validatable.validatesFormatOf = getConfigurator('format');
 Validatable.validate = getConfigurator('custom');
+Validatable.validateAsync = getConfigurator('custom', {async: true});
+Validatable.validateUniquenessOf = getConfigurator('uniqueness');
 
 // implementation of validators
 var validators = {
@@ -68,8 +70,8 @@ var validators = {
             err();
         }
     },
-    custom: function (attr, conf, err) {
-        conf.customValidator.call(this, err);
+    custom: function (attr, conf, err, cb) {
+        conf.customValidator.call(this, err, cb);
     }
 };
 
@@ -80,8 +82,8 @@ function getConfigurator(name, opts) {
     };
 }
 
-Validatable.prototype.isValid = function () {
-    var valid = true, inst = this;
+Validatable.prototype.isValid = function (callback) {
+    var valid = true, inst = this, wait = 0, async = false;
 
     // exit with success when no errors
     if (!this.constructor._validations) {
@@ -97,12 +99,29 @@ Validatable.prototype.isValid = function () {
 
     this.trigger('validation', function () {
         this.constructor._validations.forEach(function (v) {
-            if (validationFailed(inst, v)) {
+            if (v[2] && v[2].async) {
                 valid = false;
+                async = true;
+                wait += 1;
+                validationFailed(inst, v, done);
+            } else {
+                if (validationFailed(inst, v)) {
+                    valid = false;
+                }
             }
         });
     });
+
+    var asyncFail = false;
+    function done(fail) {
+        asyncFail = asyncFail || fail;
+        if (--wait === 0 && callback) {
+            callback(!asyncFail);
+        }
+    }
+
     if (valid) cleanErrors(this);
+
     return valid;
 };
 
@@ -114,7 +133,7 @@ function cleanErrors(inst) {
     });
 }
 
-function validationFailed(inst, v) {
+function validationFailed(inst, v, cb) {
     var attr = v[0];
     var conf = v[1];
     var opts = v[2] || {};
@@ -153,6 +172,11 @@ function validationFailed(inst, v) {
         inst.errors.add(attr, message);
         fail = true;
     });
+    if (cb) {
+        validatorArguments.push(function () {
+            cb(fail);
+        });
+    }
     validator.apply(inst, validatorArguments);
     return fail;
 }
diff --git a/test/validations_test.coffee b/test/validations_test.coffee
index 1cec4f2b..e4463d2c 100644
--- a/test/validations_test.coffee
+++ b/test/validations_test.coffee
@@ -231,3 +231,23 @@ it 'should validate a field using a custom validator', (test) ->
 
     test.done()
 
+it 'should validate asynchronously', (test) ->
+
+    validator = (err, done) ->
+        setTimeout =>
+            err 'async' if @name == 'bad name'
+            done()
+        , 100
+
+    User.validateAsync 'name', validator, message: async: 'hello'
+
+    user = new User validAttributes
+    test.ok not user.isValid(), 'not valid because async validation'
+    user.isValid (valid) ->
+        test.ok valid, 'valid name'
+
+        user.name = 'bad name'
+        user.isValid (valid) ->
+            test.ok not valid, 'not valid name'
+            test.done()
+