diff --git a/JSIL.Libraries/JSIL.Libraries.csproj b/JSIL.Libraries/JSIL.Libraries.csproj
index 7af588ac0..82a69f032 100644
--- a/JSIL.Libraries/JSIL.Libraries.csproj
+++ b/JSIL.Libraries/JSIL.Libraries.csproj
@@ -287,6 +287,8 @@
     <Content Include="Sources\gamepad.js" />
     <Content Include="Sources\JSIL.Bootstrap.Dynamic.js" />
     <Content Include="Sources\JSIL.Bootstrap.Text.js" />
+    <Content Include="Sources\JSIL.WebWorker.js" />
+    <Content Include="Sources\JSIL.WebWorker.Loaders.js" />
     <Content Include="Sources\StubbedBCL\JSIL.IO.js" />
     <Content Include="Sources\StubbedBCL\JSIL.XML.js" />
     <Content Include="Sources\TranslatedBCL\JSIL.Bootstrap.js" />
diff --git a/JSIL.Libraries/Sources/JSIL.WebWorker.Loaders.js b/JSIL.Libraries/Sources/JSIL.WebWorker.Loaders.js
new file mode 100644
index 000000000..073b214d3
--- /dev/null
+++ b/JSIL.Libraries/Sources/JSIL.WebWorker.Loaders.js
@@ -0,0 +1,13 @@
+var assetLoaders = {
+  "Library": function loadLibrary (filename, data, onError, onDoneLoading, state) {
+    var uri = jsilConfig.libraryRoot + filename;
+    importScripts(uri);
+  },
+  "Script": function loadScript (filename, data, onError, onDoneLoading, state) {
+    var uri = jsilConfig.scriptRoot + filename;
+    importScripts(uri);
+  },
+};
+
+function initAssetLoaders () {
+};
\ No newline at end of file
diff --git a/JSIL.Libraries/Sources/JSIL.WebWorker.js b/JSIL.Libraries/Sources/JSIL.WebWorker.js
new file mode 100644
index 000000000..c5450278b
--- /dev/null
+++ b/JSIL.Libraries/Sources/JSIL.WebWorker.js
@@ -0,0 +1,103 @@
+"use strict";
+
+JSIL.DeclareNamespace("JSIL.WebWorker", false);
+
+JSIL.WebWorker.StdOutService = function () {
+};
+
+JSIL.WebWorker.StdOutService.prototype.write = function (text) {
+  postMessage("output " + text);
+};
+
+
+JSIL.WebWorker.StdErrService = function () {
+};
+
+JSIL.WebWorker.StdErrService.prototype.write = function (text) {
+  var trimmed = String(text).trim();
+  if (trimmed[trimmed.length - 1] === "\n") {
+    text = trimmed.substr(0, trimmed.length - 1);
+  }
+
+ postMessage("error " + text);
+};
+
+(function () {
+  JSIL.Host.registerServices({
+    stdout: new JSIL.WebWorker.StdOutService(),
+    stderr: new JSIL.WebWorker.StdErrService()
+  });
+})();
+
+function reportException (e) {
+  var stack = "";
+  try {
+    stack = e.stack || "";
+  } catch (ex) {
+    stack = "";
+  }
+
+  JSIL.Host.logWriteLine("// EXCEPTION:");
+  JSIL.Host.logWriteLine(String(e));
+  if (stack.length > 0) {
+    JSIL.Host.logWriteLine("// STACK:");
+    JSIL.Host.logWriteLine(stack);
+  }
+  JSIL.Host.logWriteLine("// ENDEXCEPTION");
+
+  throw e;
+};
+
+function loadAssets (assets) {
+  for (var i = 0, l = assets.length; i < l; i++) {
+    var assetSpec = assets[i];
+  
+    var assetType = assetSpec[0];
+    var assetPath = assetSpec[1];
+    var assetData = assetSpec[2] || null;
+
+    var assetLoader = assetLoaders[assetType];
+
+    assetLoader(assetPath, assetData);
+  }
+};
+  
+// onLoad will be called from the worker.
+var onLoad = function  () {
+  initAssetLoaders();
+
+  var seenFilenames = {};
+
+  var pushAsset = function (assetSpec) {
+    var filename = assetSpec[1];
+    if (seenFilenames[filename])
+      return;
+
+    seenFilenames[filename] = true;
+    allAssetsToLoad.push(assetSpec);
+  }
+
+  var allAssetsToLoad = [];
+
+  if (typeof (assetsToLoad) !== "undefined") {
+    for (var i = 0, l = assetsToLoad.length; i < l; i++)
+      pushAsset(assetsToLoad[i]);
+  }
+
+  if (typeof (contentManifest) === "object") {
+    for (var k in contentManifest) {
+      var subManifest = contentManifest[k];
+
+      for (var i = 0, l = subManifest.length; i < l; i++)
+        pushAsset(subManifest[i]);
+
+    }
+  }
+
+  loadAssets(allAssetsToLoad);
+    JSIL.Initialize();
+    JSIL.Host.runInitCallbacks();
+    if (typeof (runMain) === "function") {
+        runMain();
+    }
+};
\ No newline at end of file
diff --git a/JSIL.Libraries/Sources/JSIL.js b/JSIL.Libraries/Sources/JSIL.js
index 6d36d9b0d..b9bdb8158 100644
--- a/JSIL.Libraries/Sources/JSIL.js
+++ b/JSIL.Libraries/Sources/JSIL.js
@@ -31,17 +31,26 @@
     globalNamespace.jsilConfig = {};
 
   if (typeof (globalNamespace.contentManifest) !== "object")
-    globalNamespace.contentManifest = {}; 
-})(this);
+      globalNamespace.contentManifest = {
+          "JSIL": []
+      };
 
-contentManifest["JSIL"] = [];
-
-var $jsilloaderstate = {
-  environment: null,
-  loadFailures: []
-};
+  globalNamespace.$jsilloaderstate = {
+    environment: null,
+    loadFailures: []
+  };
+})(typeof(self) !== "undefined" ? self : this);
 
 (function loadJSIL (config) {
+    function getLibraryPrefix(config) {
+        if (config.bclMode === "translated") {
+            return "TranslatedBCL/";
+        } else if (config.bclMode === "stubbed") {
+            return "StubbedBCL/";
+        }
+
+            return "IgnoredBCL/";
+    }
 
   function Environment_Browser (config) {
     var self = this;
@@ -67,14 +76,7 @@ var $jsilloaderstate = {
       }
     }
 
-    var libraryPrefix;
-    if (config.bclMode === "translated") {
-      libraryPrefix = "TranslatedBCL/";
-    } else if (config.bclMode === "stubbed") {
-      libraryPrefix = "StubbedBCL/";
-    } else {
-      libraryPrefix = "IgnoredBCL/";
-    }
+    var libraryPrefix = getLibraryPrefix(config);
 
     contentManifest["JSIL"].push(["Library", "JSIL.Storage.js"]);
     contentManifest["JSIL"].push(["Library", libraryPrefix + "JSIL.IO.js"]);
@@ -130,14 +132,7 @@ var $jsilloaderstate = {
     var self = this;
     this.config = config;
 
-    var libraryPrefix;
-    if (config.bclMode === "translated") {
-      libraryPrefix = "TranslatedBCL/";
-    } else if (config.bclMode === "stubbed") {
-      libraryPrefix = "StubbedBCL/";
-    } else {
-      libraryPrefix = "IgnoredBCL/";
-    }
+    var libraryPrefix = getLibraryPrefix(config);
 
     contentManifest["JSIL"].push(["Library", "JSIL.Storage.js"]);
     contentManifest["JSIL"].push(["Library", libraryPrefix + "JSIL.IO.js"]);
@@ -161,6 +156,31 @@ var $jsilloaderstate = {
     this.loadScript(libraryRoot + "JSIL.Shell.Loaders.js");
   };
 
+
+  function Environment_WebWorker(config) {
+      var self = this;
+      this.config = config;
+
+      var libraryPrefix = getLibraryPrefix(config);
+
+      contentManifest["JSIL"].push(["Library", "JSIL.Storage.js"]);
+      contentManifest["JSIL"].push(["Library", libraryPrefix + "JSIL.IO.js"]);
+      contentManifest["JSIL"].push(["Library", libraryPrefix + "JSIL.XML.js"]);
+  };
+
+  Environment_WebWorker.prototype.getUserSetting = function (key) {
+      return false;
+  };
+
+  Environment_WebWorker.prototype.loadScript = function (uri) {
+      importScripts(uri);
+  };
+
+  Environment_WebWorker.prototype.loadEnvironmentScripts = function () {
+      this.loadScript(libraryRoot + "JSIL.WebWorker.js");
+      this.loadScript(libraryRoot + "JSIL.WebWorker.Loaders.js");
+  };
+
   var priorModule = JSIL.GlobalNamespace.Module;
 
   JSIL.BeginLoadNativeLibrary = function (name) {
@@ -202,7 +222,8 @@ var $jsilloaderstate = {
 
   var environments = {
     "browser": Environment_Browser,
-    "spidermonkey_shell": Environment_SpidermonkeyShell
+    "spidermonkey_shell": Environment_SpidermonkeyShell,
+    "webworker": Environment_WebWorker
   }
 
   if (!config.environment) {