diff --git a/__tests__/client.test.ts b/__tests__/client.test.ts
index 8708170..a0e3b50 100644
--- a/__tests__/client.test.ts
+++ b/__tests__/client.test.ts
@@ -9,6 +9,7 @@ import { Variant, Variants } from '../src/types/variant';
 import { randomString } from '../src/util/randomstring';
 import AsyncStorage from '@react-native-async-storage/async-storage';
 import { ExposureTrackingProvider } from '../src/types/exposure';
+import { Exposure } from '../lib/typescript';
 
 const delay = (ms: number) => new Promise((res) => setTimeout(res, ms));
 
@@ -375,3 +376,19 @@ test('ExperimentClient.clear, clear all variants in the cache and storage', asyn
   var clearedVariants = client.all();
   expect(clearedVariants).toEqual({});
 });
+
+test('ExperimentClient.variant experiment key passed from variant to exposure', async () => {
+  let didTrack = false;
+  const client = new ExperimentClient(API_KEY, {
+    exposureTrackingProvider: {
+      track: (exposure: Exposure) => {
+        expect(exposure.experiment_key).toEqual('expKey');
+        didTrack = true;
+      },
+    },
+    source: Source.InitialVariants,
+    initialVariants: { flagKey: { value: 'value', expKey: 'expKey' } },
+  });
+  client.variant('flagKey');
+  expect(didTrack).toEqual(true);
+});
diff --git a/src/experimentClient.ts b/src/experimentClient.ts
index 011b1ce..5922460 100644
--- a/src/experimentClient.ts
+++ b/src/experimentClient.ts
@@ -377,6 +377,7 @@ export class ExperimentClient implements Client {
       variants[key] = {
         value: json[key].key,
         payload: json[key].payload,
+        expKey: json[key].expKey,
       };
     }
     this.debug('[Experiment] Received variants: ', variants);
@@ -481,6 +482,7 @@ export class ExperimentClient implements Client {
       this.exposureTrackingProvider?.track({
         flag_key: key,
         variant: variant.value,
+        experiment_key: variant.expKey,
       });
     }
   }
diff --git a/src/types/exposure.ts b/src/types/exposure.ts
index d9e88db..8746c9a 100644
--- a/src/types/exposure.ts
+++ b/src/types/exposure.ts
@@ -1,21 +1,23 @@
 /**
- * Improved exposure event for tracking exposures to Amplitude Experiment.
+ * Event object for tracking exposures to Amplitude Experiment.
  *
  * This object contains all the required information to send an `$exposure`
- * event through any SDK or CDP to experiment. The resulting exposure event
- * must follow the following definition:
+ * event through any SDK or CDP to experiment.
+ *
+ * The resulting exposure event must follow the following definition:
  * ```
  * {
  *   "event_type": "$exposure",
  *   "event_properties": {
  *     "flag_key": "<flagKey>",
- *     "variant": "<variant>"
+ *     "variant": "<variant>",
+ *     "experiment_key": "<expKey>",
  *   }
  * }
  * ```
  *
- * Where `<flagKey>` and `<variant>` are the {@link flag_key} and
- * {@link variant} variant` members on this type.
+ * Where `<flagKey>`, `<variant>`, and `<expKey>` are the {@link flag_key},
+ * {@link variant}, and {@link experiment_key} variant members on this type:
  *
  * For example, if you're using Segment for analytics:
  *
@@ -24,8 +26,20 @@
  * ```
  */
 export type Exposure = {
+  /**
+   * (Required) The key for the flag the user was exposed to.
+   */
   flag_key: string;
+  /**
+   * (Optional) The variant the user was exposed to. If null or missing, the
+   * event will not be persisted, and will unset the user property.
+   */
   variant?: string;
+  /**
+   * (Optional) The experiment key used to differentiate between multiple
+   * experiments associated with the same flag.
+   */
+  experiment_key?: string;
 };
 
 /**
@@ -72,7 +86,8 @@ export interface ExposureTrackingProvider {
    *   "event_type": "$exposure",
    *   "event_properties": {
    *     "flag_key": "<flagKey>",
-   *     "variant": "<variant>"
+   *     "variant": "<variant>",
+   *     "experiment_key": "<expKey>"
    *   }
    * }
    * ```
diff --git a/src/types/variant.ts b/src/types/variant.ts
index 9015126..0090c95 100644
--- a/src/types/variant.ts
+++ b/src/types/variant.ts
@@ -10,8 +10,12 @@ export type Variant = {
   /**
    * The attached payload, if any.
    */
-
   payload?: any;
+
+  /**
+   * The experiment key. Used to distinguish two experiments associated with the same flag.
+   */
+  expKey?: string;
 };
 
 /**