diff --git a/packages/pubsub/package.json b/packages/pubsub/package.json
index 9020bfe0cc9..b0f0669b838 100644
--- a/packages/pubsub/package.json
+++ b/packages/pubsub/package.json
@@ -61,6 +61,7 @@
     "google-proto-files": "^0.12.0",
     "grpc": "^1.6.0",
     "is": "^3.0.1",
+    "lodash.snakecase": "^4.1.1",
     "uuid": "^3.0.1"
   },
   "devDependencies": {
diff --git a/packages/pubsub/src/index.js b/packages/pubsub/src/index.js
index f8f98d72c45..93f18c030d8 100644
--- a/packages/pubsub/src/index.js
+++ b/packages/pubsub/src/index.js
@@ -173,33 +173,17 @@ PubSub.prototype.createSubscription = function(topic, name, options, callback) {
 
   options = options || {};
 
-  var subscription = this.subscription(name, options);
+  var metadata = Subscription.formatMetadata_(options);
+  var subscription = this.subscription(name, metadata);
 
-  var reqOpts = extend({
+  var reqOpts = extend(metadata, {
     topic: topic.name,
     name: subscription.name
-  }, options);
+  });
 
   delete reqOpts.gaxOpts;
   delete reqOpts.flowControl;
 
-  if (options.messageRetentionDuration) {
-    reqOpts.retainAckedMessages = true;
-
-    reqOpts.messageRetentionDuration = {
-      seconds: options.messageRetentionDuration,
-      nanos: 0
-    };
-  }
-
-  if (options.pushEndpoint) {
-    delete reqOpts.pushEndpoint;
-
-    reqOpts.pushConfig = {
-      pushEndpoint: options.pushEndpoint
-    };
-  }
-
   this.request({
     client: 'subscriberClient',
     method: 'createSubscription',
diff --git a/packages/pubsub/src/subscription.js b/packages/pubsub/src/subscription.js
index 1ecccbb1b8b..0193f81ac71 100644
--- a/packages/pubsub/src/subscription.js
+++ b/packages/pubsub/src/subscription.js
@@ -25,6 +25,7 @@ var events = require('events');
 var extend = require('extend');
 var is = require('is');
 var os = require('os');
+var snakeCase = require('lodash.snakecase');
 var util = require('util');
 
 /**
@@ -231,6 +232,34 @@ function Subscription(pubsub, name, options) {
 
 util.inherits(Subscription, events.EventEmitter);
 
+/**
+ * Formats Subscription metadata.
+ *
+ * @private
+ */
+Subscription.formatMetadata_ = function(metadata) {
+  var formatted = extend({}, metadata);
+
+  if (metadata.messageRetentionDuration) {
+    formatted.retainAckedMessages = true;
+
+    formatted.messageRetentionDuration = {
+      seconds: metadata.messageRetentionDuration,
+      nanos: 0
+    };
+  }
+
+  if (metadata.pushEndpoint) {
+    delete formatted.pushEndpoint;
+
+    formatted.pushConfig = {
+      pushEndpoint: metadata.pushEndpoint
+    };
+  }
+
+  return formatted;
+};
+
 /**
  * Format the name of a subscription. A subscription's full name is in the
  * format of projects/{projectId}/subscriptions/{subName}.
@@ -1042,9 +1071,16 @@ Subscription.prototype.setMetadata = function(metadata, gaxOpts, callback) {
     gaxOpts = {};
   }
 
+  var subscription = Subscription.formatMetadata_(metadata);
+  var fields = Object.keys(subscription).map(snakeCase);
+
+  subscription.name = this.name;
+
   var reqOpts = {
-    subscription: this.name,
-    updateMask: metadata
+    subscription: subscription,
+    updateMask: {
+      paths: fields
+    }
   };
 
   this.request({
diff --git a/packages/pubsub/system-test/pubsub.js b/packages/pubsub/system-test/pubsub.js
index fdc3a59c4b9..ff49e59388c 100644
--- a/packages/pubsub/system-test/pubsub.js
+++ b/packages/pubsub/system-test/pubsub.js
@@ -388,6 +388,34 @@ describe('pubsub', function() {
       });
     });
 
+    it('should set metadata for a subscription', function() {
+      var subscription = topic.subscription(generateSubName());
+      var threeDaysInSeconds = 3 * 24 * 60 * 60;
+
+      return subscription.create()
+        .then(function() {
+          return subscription.setMetadata({
+            messageRetentionDuration: threeDaysInSeconds
+          });
+        })
+        .then(function() {
+          return subscription.getMetadata();
+        })
+        .then(function(data) {
+          var metadata = data[0];
+
+          assert.strictEqual(metadata.retainAckedMessages, true);
+          assert.strictEqual(
+            parseInt(metadata.messageRetentionDuration.seconds, 10),
+            threeDaysInSeconds
+          );
+          assert.strictEqual(
+            parseInt(metadata.messageRetentionDuration.nanos, 10),
+            0
+          );
+        });
+    });
+
     it('should re-use an existing subscription', function(done) {
       pubsub.createSubscription(topic, SUB_NAMES[0], done);
     });
diff --git a/packages/pubsub/test/index.js b/packages/pubsub/test/index.js
index 049036469fd..595739b52c9 100644
--- a/packages/pubsub/test/index.js
+++ b/packages/pubsub/test/index.js
@@ -260,6 +260,12 @@ describe('PubSub', function() {
       name: 'subscription-name'
     };
 
+    beforeEach(function() {
+      Subscription.formatMetadata_ = function(metadata) {
+        return extend({}, metadata);
+      };
+    });
+
     it('should throw if no Topic is provided', function() {
       assert.throws(function() {
         pubsub.createSubscription();
@@ -353,13 +359,7 @@ describe('PubSub', function() {
       var expectedBody = extend({
         topic: TOPIC.name,
         name: SUB_NAME
-      }, options, {
-        pushConfig: {
-          pushEndpoint: options.pushEndpoint
-        }
-      });
-
-      delete expectedBody.pushEndpoint;
+      }, options);
 
       pubsub.topic = function() {
         return {
@@ -413,27 +413,23 @@ describe('PubSub', function() {
       pubsub.createSubscription(TOPIC, SUB_NAME, options, assert.ifError);
     });
 
-    describe('message retention', function() {
-      it('should accept a number', function(done) {
-        var threeDaysInSeconds = 3 * 24 * 60 * 60;
-
-        pubsub.request = function(config) {
-          assert.strictEqual(config.reqOpts.retainAckedMessages, true);
-
-          assert.strictEqual(
-            config.reqOpts.messageRetentionDuration.seconds,
-            threeDaysInSeconds
-          );
+    it('should format the metadata', function(done) {
+      var fakeMetadata = {};
+      var formatted = {
+        a: 'a'
+      };
 
-          assert.strictEqual(config.reqOpts.messageRetentionDuration.nanos, 0);
+      Subscription.formatMetadata_ = function(metadata) {
+        assert.strictEqual(metadata, fakeMetadata);
+        return formatted;
+      };
 
-          done();
-        };
+      pubsub.request = function(config) {
+        assert.strictEqual(config.reqOpts, formatted);
+        done();
+      };
 
-        pubsub.createSubscription(TOPIC_NAME, SUB_NAME, {
-          messageRetentionDuration: threeDaysInSeconds
-        }, assert.ifError);
-      });
+      pubsub.createSubscription(TOPIC, SUB_NAME, fakeMetadata, assert.ifError);
     });
 
     describe('error', function() {
diff --git a/packages/pubsub/test/subscription.js b/packages/pubsub/test/subscription.js
index c07bfa644a4..192421fd7d4 100644
--- a/packages/pubsub/test/subscription.js
+++ b/packages/pubsub/test/subscription.js
@@ -219,6 +219,47 @@ describe('Subscription', function() {
     });
   });
 
+  describe('formatMetadata_', function() {
+    it('should make a copy of the metadata', function() {
+      var metadata = { a: 'a' };
+      var formatted = Subscription.formatMetadata_(metadata);
+
+      assert.deepEqual(metadata, formatted);
+      assert.notStrictEqual(metadata, formatted);
+    });
+
+    it('should format messageRetentionDuration', function() {
+      var threeDaysInSeconds = 3 * 24 * 60 * 60;
+
+      var metadata = {
+        messageRetentionDuration: threeDaysInSeconds
+      };
+
+      var formatted = Subscription.formatMetadata_(metadata);
+
+      assert.strictEqual(formatted.retainAckedMessages, true);
+      assert.strictEqual(formatted.messageRetentionDuration.nanos, 0);
+
+      assert.strictEqual(
+        formatted.messageRetentionDuration.seconds,
+        threeDaysInSeconds
+      );
+    });
+
+    it('should format pushEndpoint', function() {
+      var pushEndpoint = 'http://noop.com/push';
+
+      var metadata = {
+        pushEndpoint: pushEndpoint
+      };
+
+      var formatted = Subscription.formatMetadata_(metadata);
+
+      assert.strictEqual(formatted.pushConfig.pushEndpoint, pushEndpoint);
+      assert.strictEqual(formatted.pushEndpoint, undefined);
+    });
+  });
+
   describe('formatName_', function() {
     it('should format name', function() {
       var formattedName = Subscription.formatName_(PROJECT_ID, SUB_NAME);
@@ -1797,16 +1838,37 @@ describe('Subscription', function() {
   });
 
   describe('setMetadata', function() {
-    var METADATA = {};
+    var METADATA = {
+      pushEndpoint: 'http://noop.com/push'
+    };
+
+    beforeEach(function() {
+      Subscription.formatMetadata_ = function(metadata) {
+        return extend({}, metadata);
+      };
+    });
 
     it('should make the correct request', function(done) {
+      var formattedMetadata = {
+        pushConfig: {
+          pushEndpoint: METADATA.pushEndpoint
+        }
+      };
+
+      var expectedBody = extend({
+        name: SUB_FULL_NAME
+      }, formattedMetadata);
+
+      Subscription.formatMetadata_ = function(metadata) {
+        assert.strictEqual(metadata, METADATA);
+        return formattedMetadata;
+      };
+
       subscription.request = function(config, callback) {
         assert.strictEqual(config.client, 'subscriberClient');
         assert.strictEqual(config.method, 'updateSubscription');
-        assert.deepEqual(config.reqOpts, {
-          subscription: subscription.name,
-          updateMask: METADATA
-        });
+        assert.deepEqual(config.reqOpts.subscription, expectedBody);
+        assert.deepEqual(config.reqOpts.updateMask, { paths: ['push_config'] });
         callback(); // the done fn
       };