diff --git a/README.md b/README.md
index 09038d2..08a7d02 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,10 @@ npm install sparkpost
     * Required: no
     * Type: `String`
     * Default: `v1`
+* `options.stackIdentity`
+    * Required: no
+    * Type: `String`
+    * An optional identifier to include in the User-Agent header. e.g. `product/1.0.0`
 * `options.headers`
     * Required: no
     * Type: `Object`
diff --git a/lib/sparkpost.js b/lib/sparkpost.js
index 67f1b2c..b9c07e1 100644
--- a/lib/sparkpost.js
+++ b/lib/sparkpost.js
@@ -5,7 +5,7 @@ var version = require('../package.json').version
   , Promise = require('./Promise')
   , request = require('request')
   , _ = require('lodash')
-  , defaults, resolveUri, handleOptions, createSparkPostError, SparkPost;
+  , defaults, resolveUri, handleOptions, createSparkPostError, createVersionStr, SparkPost;
 
 //REST API Config Defaults
 defaults = {
@@ -45,6 +45,14 @@ createSparkPostError = function(res, body) {
   return err;
 };
 
+createVersionStr = function(version, options) {
+  let versionStr = 'node-sparkpost/' + version + ' node.js/' + process.version;
+  if (options.stackIdentity) {
+    versionStr += options.stackIdentity + ' ' + versionStr;
+  }
+  return versionStr;
+};
+
 SparkPost = function(apiKey, options) {
 
   options = handleOptions(apiKey, options);
@@ -60,7 +68,7 @@ SparkPost = function(apiKey, options) {
 
   // setting up default headers
   this.defaultHeaders = _.merge({
-    'User-Agent': 'node-sparkpost/' + this.version
+    'User-Agent': createVersionStr(version, options)
     , 'Content-Type': 'application/json'
   }, options.headers);
 
diff --git a/test/spec/sparkpost.spec.js b/test/spec/sparkpost.spec.js
index 12ed294..b3ab7cf 100644
--- a/test/spec/sparkpost.spec.js
+++ b/test/spec/sparkpost.spec.js
@@ -5,10 +5,12 @@ var chai = require('chai')
   , sinon = require('sinon')
   , zlib = require('zlib')
   , nock = require('nock')
-  , SparkPost = require('../../lib/sparkpost');
+  , SparkPost = require('../../lib/sparkpost')
+  , libVersion = require('../../package.json').version;
 
 chai.use(require('sinon-chai'));
 
+
 describe('SparkPost Library', function() {
 
   it('should be a constructor', function() {
@@ -81,6 +83,48 @@ describe('SparkPost Library', function() {
     expect(client.debug).to.equal(true);
   });
 
+  function checkUserAgent(clientOptions, checkFn, done) {
+    let req = {
+        method: 'GET'
+        , uri: 'get/test'
+        , json: true
+        , debug: true
+    }
+    , client;
+
+    nock('https://api.sparkpost.com')
+      .get('/api/v1/get/test')
+      .reply(200, function() {
+        expect(this.req.headers).to.have.property('user-agent');
+        checkFn(this.req.headers['user-agent']);
+        return { ok: true };
+      });
+
+    client = new SparkPost('123456789', clientOptions);
+    client.request(req, done);
+  }
+
+  it('should allow users to self identify in user-agent', function(done) {
+    let options = {
+      stackIdentity: 'phantasmatron/1.1.3.8'
+    }
+    checkUserAgent(options, function(userAgent) {
+      expect(userAgent).to.include(options.stackIdentity);
+    }, done);
+  });
+
+  it('should include lib version in user-agent', function(done) {
+    checkUserAgent({}, function(userAgent) {
+      expect(userAgent).to.include('node-sparkpost/' + libVersion);
+    }, done);
+  });
+
+  it('should include Node.JS version in user-agent', function(done) {
+    checkUserAgent({}, function(userAgent) {
+      expect(userAgent).to.include('node.js/' + process.version);
+    }, done);
+  });
+
   describe('request method', function() {
     var client;