diff --git a/src/amplitude-client.js b/src/amplitude-client.js
index 1f42a3f2..0f43917d 100644
--- a/src/amplitude-client.js
+++ b/src/amplitude-client.js
@@ -1269,6 +1269,7 @@ AmplitudeClient.prototype._logEvent = function _logEvent(
     eventProperties = eventProperties || {};
     groups = groups || {};
     groupProperties = groupProperties || {};
+
     var event = {
       device_id: this.options.deviceId,
       user_id: this.options.userId,
@@ -1297,6 +1298,14 @@ AmplitudeClient.prototype._logEvent = function _logEvent(
       user_agent: this._userAgent,
     };
 
+    if (_isObservePlanSet(this)) {
+      event.plan = {
+        branch: this.options.plan.branch || undefined,
+        source: this.options.plan.source || undefined,
+        version: this.options.plan.version || undefined,
+      };
+    }
+
     if (eventType === Constants.IDENTIFY_EVENT || eventType === Constants.GROUP_IDENTIFY_EVENT) {
       this._unsentIdentifys.push({ event, callback, errorCallback });
       this._limitEventsQueued(this._unsentIdentifys);
@@ -1317,6 +1326,10 @@ AmplitudeClient.prototype._logEvent = function _logEvent(
   }
 };
 
+const _isObservePlanSet = function _isObservePlanSet(scope) {
+  return scope.options.plan && (scope.options.plan.source || scope.options.plan.branch || scope.options.plan.version);
+};
+
 var _shouldTrackField = function _shouldTrackField(scope, field) {
   return !!scope.options.trackingOptions[field];
 };
diff --git a/src/options.js b/src/options.js
index 375032e1..cffa1112 100644
--- a/src/options.js
+++ b/src/options.js
@@ -28,6 +28,10 @@ import language from './language';
  * @property {boolean} [optOut=`false`] -  Whether or not to disable tracking for the current user.
  * @property {function} [onError=`() => {}`] - Function to call on error.
  * @property {function} [onExitPage=`() => {}`] - Function called when the user exits the browser. Useful logging on page exit.
+ * @property {Object} [plan] Tracking plan properties
+ * @property {string} [plan.branch] The tracking plan branch name e.g. "main"
+ * @property {string} [plan.source] The tracking plan source e.g. "web"
+ * @property {string} [plan.version] The tracking plan version e.g. "1", "15"
  * @property {string} [platform=`Web`] -  Platform device is running on. Defaults to `Web` (browser, including mobile browsers).
  * @property {number} [savedMaxCount=`1000`] -  Maximum number of events to save in localStorage. If more events are logged while offline, then old events are removed.
  * @property {boolean} [saveEvents=`true`] -  If `true`, saves events to localStorage and removes them upon successful upload. *Note: Without saving events, events may be lost if the user navigates to another page before the events are uploaded.*
@@ -67,6 +71,11 @@ export default {
   optOut: false,
   onError: () => {},
   onExitPage: () => {},
+  plan: {
+    branch: '',
+    source: '',
+    version: '',
+  },
   platform: 'Web',
   savedMaxCount: 1000,
   saveEvents: true,
diff --git a/test/amplitude-client.js b/test/amplitude-client.js
index 1d2dc474..2a11551f 100644
--- a/test/amplitude-client.js
+++ b/test/amplitude-client.js
@@ -855,6 +855,18 @@ describe('AmplitudeClient', function () {
 
       amplitude.cookieStorage.options.restore();
     });
+
+    it('should set observer plan options', function () {
+      var amplitude = new AmplitudeClient('observer plan');
+      var plan = {
+        branch: 'my-feature-branch',
+        source: 'web',
+        version: '1.0.0',
+      };
+      amplitude.init(apiKey, null, { plan: plan });
+
+      assert.deepEqual(amplitude.options.plan, plan);
+    });
   });
 
   describe('runQueuedFunctions', function () {