diff --git a/README.md b/README.md
index 63ced6f..abfd9ac 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,10 @@ ENV.serviceWorker = {
   skipWaiting: true,
   swIncludeFiles: [
     'bower_components/pouchdb/dist/pouchdb.js'
-  ]
+  ],
+  swEnvironment: {
+    foo: ENV.foo,
+  }
 };
 ```
 The following options are available:
@@ -52,6 +55,7 @@ The following options are available:
 * **fallback** - Array of URLs with fallbacks when the resource isn't available via network or cache.
 * **skipWaiting** - Allows a simple page refresh to update the app.  Defaults to true.
 * **swIncludeFiles** - Array of files to include in the generated service worker.  This is intended to allow inclusion of vendor files in your service worker.  For example, if you wanted to run [PouchDB](http://pouchdb.com/) replication in a service worker, you need to include PouchDB in your service worker.
+* **swEnvironment** - object that will be injected as-is in the service worker script as a top-level `swEnvironment` variable.
 
 ####Routing Options
 The following options allow you to specify routes that use [sw-toolbox's built-in handlers](https://github.com/GoogleChrome/sw-toolbox#built-in-handlers).  Each of these options accepts an array of URLs that can be strings or [regular expressions](https://github.com/GoogleChrome/sw-toolbox#regular-expression-routes).
diff --git a/lib/service-worker.js b/lib/service-worker.js
index f6973a6..e740db2 100644
--- a/lib/service-worker.js
+++ b/lib/service-worker.js
@@ -39,6 +39,7 @@ var BroccoliServiceWorker = function BroccoliServiceWorker(inTree, options) {
   }
   this.swIncludeTree = options.swIncludeTree;
   this.swIncludeFiles = options.swIncludeFiles;
+  this.swEnvironment = options.swEnvironment || {};
 };
 
 BroccoliServiceWorker.prototype = Object.create(brocWriter.prototype);
@@ -60,10 +61,12 @@ BroccoliServiceWorker.prototype.write = function(readTree, destDir) {
   });
   var swIncludeFiles = this.swIncludeFiles;
   var swIncludeTree = this.swIncludeTree;
+  var swEnvironment = this.swEnvironment;
 
   return readSwIncludeTree(readTree, this.swIncludeTree).then(function(swIncludeDir){
     return readTree(serviceWorkerTree).then(function (srcDir) {
       var lines = [];
+      lines.push("var swEnvironment = " + JSON.stringify(swEnvironment) + ";");
       lines.push("importScripts('"+toolboxLocation+"');");
       lines.push("var CACHE_PREFIX = 'brocsw-v';");
       lines.push("var CACHE_VERSION = CACHE_PREFIX+'"+(new Date()).getTime()+"';");