diff --git a/spec/src/modules/tracker.js b/spec/src/modules/tracker.js
index 924e7e03..a96661c8 100644
--- a/spec/src/modules/tracker.js
+++ b/spec/src/modules/tracker.js
@@ -68,20 +68,21 @@ describe(`ConstructorIO - Tracker${bundledDescriptionSuffix}`, () => {
   });
 
   describe('trackSessionStart', () => {
-    it('Should respond with a valid response', (done) => {
+    it.only('Should respond with a valid response', (done) => {
       const { tracker } = new ConstructorIO({
         apiKey: testApiKey,
         fetch: fetchSpy,
+        constructorABCell: true,
         ...requestQueueOptions,
       });
 
       tracker.on('success', (responseParams) => {
         const requestParams = helpers.extractUrlParamsFromFetch(fetchSpy);
-
         // Request
         expect(fetchSpy).to.have.been.called;
         expect(requestParams).to.have.property('key');
         expect(requestParams).to.have.property('i');
+        expect(requestParams).to.have.property('is_constructor_ab_cell');
         expect(requestParams).to.have.property('s');
         expect(requestParams).to.have.property('action').to.equal('session_start');
         expect(requestParams).to.have.property('c').to.equal(clientVersion);
@@ -91,7 +92,6 @@ describe(`ConstructorIO - Tracker${bundledDescriptionSuffix}`, () => {
         // Response
         expect(responseParams).to.have.property('method').to.equal('GET');
         expect(responseParams).to.have.property('message').to.equal('ok');
-
         done();
       });
 
diff --git a/src/constructorio.js b/src/constructorio.js
index 1503f476..887c00da 100644
--- a/src/constructorio.js
+++ b/src/constructorio.js
@@ -75,6 +75,7 @@ class ConstructorIO {
       idOptions,
       beaconMode,
       networkParameters,
+      constructorABCell,
     } = options;
 
     if (!apiKey || typeof apiKey !== 'string') {
@@ -114,6 +115,7 @@ class ConstructorIO {
       sendTrackingEvents,
       sendReferrerWithTrackingEvents,
       eventDispatcher,
+      constructorABCell,
       beaconMode: (beaconMode === false) ? false : true, // Defaults to 'true',
       networkParameters: networkParameters || {},
     };
diff --git a/src/modules/tracker.js b/src/modules/tracker.js
index 22a26e6d..3c288a4c 100644
--- a/src/modules/tracker.js
+++ b/src/modules/tracker.js
@@ -15,6 +15,7 @@ function applyParams(parameters, options) {
     testCells,
     requestMethod,
     beaconMode,
+    constructorABCell,
   } = options;
   const { host, pathname } = helpers.getWindowLocation();
   const sendReferrerWithTrackingEvents = (options.sendReferrerWithTrackingEvents === false)
@@ -22,6 +23,10 @@ function applyParams(parameters, options) {
     : true; // Defaults to 'true'
   let aggregateParams = Object.assign(parameters);
 
+  if (typeof constructorABCell === 'boolean') {
+    aggregateParams.is_constructor_ab_cell = constructorABCell;
+  }
+
   if (version) {
     aggregateParams.c = version;
   }