diff --git a/bin/marionette-mocha b/bin/marionette-mocha
index 8f02103..4488d79 100755
--- a/bin/marionette-mocha
+++ b/bin/marionette-mocha
@@ -31,6 +31,18 @@ function requireReporter(path) {
   }
 }
 
+/**
+ * Helper to import the marionette desired capabilities
+ */
+function importDesiredCapabilities(path) {
+  try {
+    return require(path);
+  } catch (e) {
+    // Can not parse marionette desired capabilities file.
+    return;
+  }
+}
+
 /**
 Convert this host log argument into a stream (not done as a type to avoid
 destructive operations when calling --help)
@@ -108,6 +120,12 @@ parser.addArgument(['--mocha-flags'], {
   action: 'storeTrue'
 });
 
+parser.addArgument(['--marionette-capabilities'], {
+  type: importDesiredCapabilities,
+  dest: 'desiredCapabilities',
+  help: 'Path tp marionette desired capabilities file (*.json)'
+});
+
 var argv = ['test/', 'tests/', '.'].reduce(function(argv, path) {
   var optsFile = fsPath.join(path, OPTS_FILE);
   if (!fs.existsSync(optsFile)) {
@@ -192,6 +210,8 @@ function main(argv) {
 
     profileBase: args[0].profileBase,
 
+    desiredCapabilities: args[0].desiredCapabilities,
+
     hostLog: hostLogStream(args[0].hostLog),
 
     verbose: args[0].verbose
diff --git a/lib/childrunner.js b/lib/childrunner.js
index 91dc326..33fdf26 100644
--- a/lib/childrunner.js
+++ b/lib/childrunner.js
@@ -56,6 +56,9 @@ function ChildRunner(options) {
   // base details used in every profile
   this.profileBase = options.profileBase;
 
+  // optional marionette desired capabilities
+  this.desiredCapabilities = options.desiredCapabilities;
+
   this._nextRemoteId = 1;
   this._verbose = !!options.verbose;
   this.remotes = {};
@@ -414,6 +417,15 @@ ChildRunner.prototype = {
     process.nextTick(next);
   },
 
+  /**
+   * Encode the data in base64 + json
+   * @param  {JSON} data Data to be encoded.
+   * @return {String} base64 encoded string
+   */
+  _encode: function(data) {
+    return new Buffer(JSON.stringify(data)).toString('base64');
+  },
+
   /**
    * Spawn the process for the mocha child runner.
    */
@@ -423,10 +435,8 @@ ChildRunner.prototype = {
       ['--reporter', PROXY_BINARY]
     );
 
-    // encode the metadata in base64 + json
-    var metadata = new Buffer(
-      JSON.stringify(this.host.constructor.metadata)
-    ).toString('base64');
+    // encode the metadata
+    var metadata = this._encode(this.host.constructor.metadata);
 
     // pass all environment variables to the child...
     var env = {};
@@ -444,6 +454,11 @@ ChildRunner.prototype = {
     // turn on the fork options so we get ipc messages.
     options.env[reporter.FORK_ENV] = 1;
 
+    if (this.desiredCapabilities) {
+      // Encode and pass desired capabilities to the child
+      options.env.DESIRED_CAPABILITIES = this._encode(this.desiredCapabilities);
+    }
+
     this.process = fork(MOCHA_BINARY, argv, options);
     this.runner = new Consumer(this.process);
 
diff --git a/lib/parentrunner.js b/lib/parentrunner.js
index f46f875..953ae6a 100644
--- a/lib/parentrunner.js
+++ b/lib/parentrunner.js
@@ -65,7 +65,8 @@ ParentRunner.prototype = {
       profileBuilder: options.profileBuilder,
       profileBase: options.profileBase,
       verbose: options.verbose,
-      hostLog: options.hostLog
+      hostLog: options.hostLog,
+      desiredCapabilities: options.desiredCapabilities
     });
 
     // keep track of all children- mostly for future use.
diff --git a/lib/runtime/hostmanager.js b/lib/runtime/hostmanager.js
index dd90f7b..f1fa8f2 100644
--- a/lib/runtime/hostmanager.js
+++ b/lib/runtime/hostmanager.js
@@ -42,6 +42,7 @@ HostManager.prototype = {
   createHost: function(profile, driver, desiredCapabilities) {
     profile = profile || {};
     driver = driver || Marionette.Drivers.TcpSync;
+    desiredCapabilities = desiredCapabilities || this.desiredCapabilities;
 
     debug('create host', profile);
 
diff --git a/lib/ui.js b/lib/ui.js
index 29d4ee0..9fa043b 100644
--- a/lib/ui.js
+++ b/lib/ui.js
@@ -14,30 +14,28 @@ var Suite = require('mocha/lib/suite'),
     utils = require('mocha/lib/utils');
 
 /**
- * Internal method designed to attempt to find the metadata for this child
- * process based on the environment variable CHILD_METADATA.
+ * Internal method designed to attempt to find the env data for this child
+ * process based on the environment variable.
  *
  * The environment variable is expected to be a base64 encoded string which can
  * be parsed as JSON.
  *
+ * @param {String} name environment variable name.
  *
  * @private
  * @return {Object}
  */
-function findMetadata() {
-  if (!process.env.CHILD_METADATA)
+function decode(name) {
+  var data = process.env[name];
+  if (!data) {
     return {};
-
+  }
   try {
-    return JSON.parse(
-      new Buffer(process.env.CHILD_METADATA, 'base64').toString()
-    );
+    return JSON.parse(new Buffer(data, 'base64').toString());
   } catch (e) {
-    console.error('could not parse CHILD_METADATA');
+    console.error('could not parse ' + name);
     return {};
   }
-
-  return result;
 }
 
 /**
@@ -101,9 +99,10 @@ module.exports = function(suite) {
      *
      * @type {Object}
      */
-    context.marionette.metadata = findMetadata();
+    context.marionette.metadata = decode('CHILD_METADATA');
 
     // Setup global state manager for the marionette runtime.
+    manager.desiredCapabilities = decode('DESIRED_CAPABILITIES');
     context.marionette._manager = manager;
     context.marionette.client = manager.createHost.bind(manager);
     context.marionette.plugin = manager.addPlugin.bind(manager);
diff --git a/test/bin/fixtures/capabilities.json b/test/bin/fixtures/capabilities.json
new file mode 100644
index 0000000..3862a62
--- /dev/null
+++ b/test/bin/fixtures/capabilities.json
@@ -0,0 +1,3 @@
+{
+  "desiredCapability": true
+}
diff --git a/test/bin/marionette-mocha.js b/test/bin/marionette-mocha.js
index 3f21fe7..8327bcd 100644
--- a/test/bin/marionette-mocha.js
+++ b/test/bin/marionette-mocha.js
@@ -143,6 +143,26 @@ suite('mocha integration', function() {
     });
   });
 
+  suite('--marionette-capabilities', function() {
+    var result,
+    capabilitiesPath = __dirname + '/fixtures/capabilities.json',
+    expected = JSON.stringify({ capabilities: require(capabilitiesPath) }),
+    argv = [
+      '--marionette-capabilities', capabilitiesPath,
+      '--host-log', 'stdout',
+      __dirname + '/fixtures/marionettetest'
+    ];
+
+    setup(function(done) {
+      var proc = spawnMarionette(argv);
+      result = waitForProcess(proc, done);
+    });
+
+    test('desired capabilities are set', function() {
+      assert.ok(result.stdoutRaw.indexOf(expected) !== -1);
+    });
+  });
+
   suite('--host-log=stdout', function() {
     var result,
     argv = [