diff --git a/bower.json b/bower.json
index aae3490..05b063c 100644
--- a/bower.json
+++ b/bower.json
@@ -10,7 +10,8 @@
   ],
   "devDependencies": {
     "web-component-tester": "^4.0.0",
-    "webcomponentsjs": "webcomponents/webcomponentsjs#^0.7.0"
+    "webcomponentsjs": "webcomponents/webcomponentsjs#^0.7.0",
+    "webcomponentsjs-v1": "webcomponents/webcomponentsjs#v1"
   },
   "main": "test-fixture.html",
   "ignore": []
diff --git a/test-fixture.html b/test-fixture.html
index 37a243e..339b1a6 100644
--- a/test-fixture.html
+++ b/test-fixture.html
@@ -235,11 +235,18 @@
 
     forcePolyfillAttachedStateSynchrony: function () {
       // Force synchrony in attachedCallback and detachedCallback where
-      // implemented, in the event that we are dealing with the async Web
-      // Components Polyfill.
-      if (window.CustomElements && window.CustomElements.takeRecords) {
+      // implemented, in the event that we are dealing with one of these async
+      // polyfills:
+      // 1. Web Components CustomElements polyfill (v1 or v0).
+      if (window.customElements && window.customElements.flush) {
+        window.customElements.flush();
+      } else if (window.CustomElements && window.CustomElements.takeRecords) {
         window.CustomElements.takeRecords();
       }
+      // 2. ShadyDOM polyfill.
+      if (window.ShadyDOM) {
+        window.ShadyDOM.flush();
+      }
     },
 
     collectElementChildren: function (parent) {
@@ -313,9 +320,20 @@
     });
 
   try {
-    document.registerElement('test-fixture', {
-      prototype: TestFixturePrototype
-    });
+    if (window.customElements) {
+      function TestFixture() {
+        return ((window.Reflect && Reflect.construct) ?
+            Reflect.construct(HTMLElement, [], TestFixture)
+            : HTMLElement.call(this)) || this;
+      }
+      TestFixture.prototype = TestFixturePrototype;
+      TestFixture.prototype.constructor = TestFixture;
+      customElements.define('test-fixture', TestFixture);
+    } else {
+      document.registerElement('test-fixture', {
+        prototype: TestFixturePrototype
+      });
+    }
   } catch (e) {
     if (window.WCT) {
       console.warn('if you are using WCT, you do not need to manually import test-fixture.html');
diff --git a/test/index.html b/test/index.html
index a00d9a2..6366568 100644
--- a/test/index.html
+++ b/test/index.html
@@ -15,14 +15,15 @@
     <script src="../../webcomponentsjs/webcomponents-lite.js"></script>
     <script src="../../web-component-tester/browser.js"></script>
 
-    <link rel="import" href="../../polymer/polymer.html">
-
   </head>
   <body>
     <script>
       WCT.loadSuites([
-        'test-fixture.html',
-        'handle-multiple-registrations.html'
+        'test-fixture.html', // shady
+        'test-fixture.html?dom=shadow', // shadow
+        'test-fixture-v1.html?wc-shadydom=true&wc-ce=true', // shady
+        'test-fixture-v1.html', // shadow
+        'handle-multiple-registrations.html',
       ]);
     </script>
   </body>
diff --git a/test/test-fixture-v1.html b/test/test-fixture-v1.html
new file mode 100644
index 0000000..e7bba84
--- /dev/null
+++ b/test/test-fixture-v1.html
@@ -0,0 +1,262 @@
+<!doctype html>
+<!--
+@license
+Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
+The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+<html>
+<head>
+  <title>test-fixture</title>
+
+  <script>
+    // Save original HTMLElement constructor since customElements v1 polyfill
+    // overrides it https://github.com/webcomponents/webcomponentsjs/issues/623
+    var _HTMLElement = window.HTMLElement;
+  </script>
+
+  <script src="../../webcomponentsjs-v1/webcomponents-lite.js"></script>
+  <script src="../../web-component-tester/browser.js"></script>
+
+  <link rel="import" id="test-fixture-import" href="../test-fixture.html">
+  <script src="../test-fixture-mocha.js"></script>
+</head>
+<body>
+  <script>
+    (function() {
+      function XCustom() {
+        if (window.Reflect) {
+          return Reflect.construct(HTMLElement, [], XCustom)
+        }
+        return HTMLElement.call(this) || this;
+      }
+
+      XCustom.constructor = XCustom;
+      XCustom.prototype = Object.create(HTMLElement.prototype);
+      XCustom.prototype.onDetached = function() {};
+      XCustom.prototype.disconnectedCallback = function() {
+        this.onDetached();
+      };
+
+      customElements.define('x-custom', XCustom);
+    })();
+  </script>
+  <test-fixture id="TrivialFixture">
+    <template>
+      <div id="Foo"></div>
+    </template>
+  </test-fixture>
+  <test-fixture id="ComplexDomFixture">
+    <template>
+      <div id="Bar">
+        <div id="BarChild"></div>
+      </div>
+      <div id="BarSibling"></div>
+    </template>
+  </test-fixture>
+  <test-fixture id="MultiTemplateFixture">
+    <template>
+      <div id="Baz"></div>
+    </template>
+    <template>
+      <div id="Qux"></div>
+      <div id="QuxSibling"></div>
+    </template>
+  </test-fixture>
+  <test-fixture id="CommentedSingleChildFixture">
+    <template>
+      <!-- comment -->
+      <!-- comment -->
+      <div id="Foo"></div>
+      <!-- comment -->
+    </template>
+  </test-fixture>
+  <test-fixture id="CommentedMultiChildFixture">
+    <template>
+      <!-- comment -->
+      <div id="Bar">
+        <div id="BarChild"></div>
+      </div>
+      <!-- comment -->
+      <!-- comment -->
+      <div id="BarSibling"></div>
+      <!-- comment -->
+      <div id="Baz"></div>
+    </template>
+  </test-fixture>
+  <test-fixture id="AttachedFixture">
+    <template>
+      <x-custom></x-custom>
+    </template>
+  </test-fixture>
+  <script>
+describe('test-fixture import', function() {
+  it('loads from test-fixture import', function() {
+    var importNode = document.getElementById('test-fixture-import');
+    expect(importNode.import).to.not.be.null;
+  });
+});
+describe('<test-fixture>', function () {
+  var trivialFixture;
+  var complexDomFixture;
+  var multiTemplateFixture;
+  var commentedSingleChildFixture;
+  var commentedMultiChildFixture;
+
+  beforeEach(function () {
+    trivialFixture = document.getElementById('TrivialFixture');
+    complexDomFixture = document.getElementById('ComplexDomFixture');
+    multiTemplateFixture = document.getElementById('MultiTemplateFixture');
+    commentedSingleChildFixture = document.getElementById('CommentedSingleChildFixture');
+    commentedMultiChildFixture = document.getElementById('CommentedMultiChildFixture');
+  });
+
+  afterEach(function () {
+    trivialFixture.restore();
+    complexDomFixture.restore();
+    multiTemplateFixture.restore();
+    commentedSingleChildFixture.restore();
+    commentedMultiChildFixture.restore();
+  });
+
+  describe('an stamped-out fixture', function () {
+    var attachedFixture;
+    var element;
+
+    beforeEach(function () {
+      attachedFixture = document.getElementById('AttachedFixture');
+      element = attachedFixture.create();
+    });
+
+    afterEach(function () {
+      attachedFixture.restore();
+    });
+
+    it('detaches the fixtured DOM when it is restored', function () {
+      var detached = false;
+
+      element.onDetached = function () {
+        detached = true;
+      };
+
+      attachedFixture.restore();
+      expect(detached).to.be.eql(true);
+    });
+  });
+
+  describe('when create is called', function () {
+    var el;
+
+    beforeEach(function () {
+      el = trivialFixture.create();
+    });
+
+    it('clones all template fragments within itself', function () {
+      expect(el).to.be.ok;
+      expect(document.getElementById('Foo')).to.be.ok;
+    });
+
+    it('detaches all fixture templates from itself', function () {
+      expect(trivialFixture.querySelectorAll('template').length).to.be.equal(0);
+    });
+
+    describe('and then restore is called', function () {
+      beforeEach(function () {
+        trivialFixture.restore();
+      });
+
+      it('re-attaches all fixture templates', function () {
+        expect(trivialFixture.querySelectorAll('template').length).to.be.equal(1);
+      });
+
+      it('removes all cloned elements from itself', function () {
+        expect(document.getElementById('Foo')).to.not.be.ok;
+      });
+    });
+
+    describe('for a dom with a single root element', function () {
+      it('returns a reference to the root element', function () {
+        expect(el).to.be.instanceOf(_HTMLElement);
+      });
+    });
+
+    describe('for a complex dom', function () {
+      var els;
+
+      beforeEach(function () {
+        els = complexDomFixture.create();
+      });
+
+      it('fixtures all the dom elements in the template', function () {
+        expect(document.getElementById('Bar')).to.be.ok;
+        expect(document.getElementById('BarSibling')).to.be.ok;
+        expect(document.getElementById('BarChild')).to.be.ok;
+      });
+
+      it('returns an array of root elements', function () {
+        expect(els).to.be.instanceOf(Array);
+        expect(els[0]).to.be.instanceOf(_HTMLElement);
+        expect(els[1]).to.be.instanceOf(_HTMLElement);
+      });
+    });
+
+    describe('when there are multiple templates', function () {
+      var groups;
+
+      beforeEach(function () {
+        groups = multiTemplateFixture.create();
+      });
+
+      it('fixtures elements from all of the templates', function () {
+        expect(document.getElementById('Baz')).to.be.ok;
+        expect(document.getElementById('Qux')).to.be.ok;
+      });
+
+      it('returns an array with elements grouped by template', function () {
+        expect(groups).to.be.instanceOf(Array);
+        expect(groups[0]).to.be.instanceOf(_HTMLElement);
+        expect(groups[1]).to.be.instanceOf(Array);
+        expect(groups[1][0]).to.be.instanceOf(_HTMLElement);
+        expect(groups[1][1]).to.be.instanceOf(_HTMLElement);
+      });
+    });
+
+    describe('when there are comments in the template', function() {
+      var el;
+      var els;
+
+      beforeEach(function () {
+        el = commentedSingleChildFixture.create();
+        els = commentedMultiChildFixture.create();
+      });
+
+      it('returns a single element if the template has a single child', function() {
+        expect(el).to.be.instanceOf(_HTMLElement);
+      });
+
+      it('returns multiple elements if the template has multiple children', function() {
+        expect(els).to.be.instanceOf(Array);
+        expect(els.length).to.equal(3);
+      });
+    });
+  });
+
+  describe('when the fixture global is called', function () {
+    var el;
+
+    beforeEach(function () {
+      el = fixture('TrivialFixture');
+    });
+
+    it('generates a DOM fragment from the associated fixture', function () {
+      expect(el).to.be.equal(document.getElementById('Foo'));
+    });
+  });
+});
+  </script>
+
+</body>
+</html>
diff --git a/test/test-fixture.html b/test/test-fixture.html
index 00788c8..197bb91 100644
--- a/test/test-fixture.html
+++ b/test/test-fixture.html
@@ -14,9 +14,9 @@
 
   <script src="../../webcomponentsjs/webcomponents-lite.js"></script>
   <script src="../../web-component-tester/browser.js"></script>
-  <script src="../test-fixture-mocha.js"></script>
 
   <link rel="import" id="test-fixture-import" href="../test-fixture.html">
+  <script src="../test-fixture-mocha.js"></script>
 </head>
 <body>
   <script>
