diff --git a/package.json b/package.json
index 5fc19a0..f3517e3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk",
-  "version": "3.4.0",
+  "version": "3.5.0",
   "description": "Eppo SDK for client-side JavaScript applications",
   "main": "dist/index.js",
   "files": [
@@ -61,4 +61,4 @@
   "dependencies": {
     "@eppo/js-client-sdk-common": "4.0.0"
   }
-}
+}
\ No newline at end of file
diff --git a/src/index.spec.ts b/src/index.spec.ts
index 971bb4c..668faeb 100644
--- a/src/index.spec.ts
+++ b/src/index.spec.ts
@@ -191,6 +191,7 @@ describe('EppoJSClient E2E test', () => {
       apiKey,
       baseUrl,
       assignmentLogger: mockLogger,
+      forceReinitialize: true,
     });
   });
 
@@ -335,6 +336,7 @@ describe('EppoJSClient E2E test', () => {
         apiKey,
         baseUrl,
         assignmentLogger: mockLogger,
+        forceReinitialize: true,
       });
     });
 
@@ -494,6 +496,61 @@ describe('initialization options', () => {
     expect(callCount).toBe(2);
   });
 
+  it('do not reinitialize if already initialized', async () => {
+    let callCount = 0;
+
+    global.fetch = jest.fn(() => {
+      callCount += 1;
+      return Promise.resolve({
+        ok: true,
+        status: 200,
+        json: () => Promise.resolve(mockConfigResponse),
+      });
+    }) as jest.Mock;
+
+    await init({
+      apiKey,
+      baseUrl,
+      assignmentLogger: mockLogger,
+    });
+
+    await init({
+      apiKey,
+      baseUrl,
+      assignmentLogger: mockLogger,
+    });
+
+    expect(callCount).toBe(1);
+  });
+
+  it('force reinitialize', async () => {
+    let callCount = 0;
+
+    global.fetch = jest.fn(() => {
+      callCount += 1;
+      return Promise.resolve({
+        ok: true,
+        status: 200,
+        json: () => Promise.resolve(mockConfigResponse),
+      });
+    }) as jest.Mock;
+
+    await init({
+      apiKey,
+      baseUrl,
+      assignmentLogger: mockLogger,
+    });
+
+    await init({
+      apiKey,
+      baseUrl,
+      assignmentLogger: mockLogger,
+      forceReinitialize: true,
+    });
+
+    expect(callCount).toBe(2);
+  });
+
   it('polls after successful init if configured to do so', async () => {
     let callCount = 0;
 
@@ -723,6 +780,7 @@ describe('initialization options', () => {
       apiKey,
       baseUrl,
       assignmentLogger: mockLogger,
+      forceReinitialize: true,
     });
 
     expect(fetchCallCount).toBe(1);
@@ -735,6 +793,7 @@ describe('initialization options', () => {
       baseUrl: 'https://thisisabaddomainforthistest.com',
       assignmentLogger: mockLogger,
       useExpiredCache: true,
+      forceReinitialize: true,
     });
 
     // Should serve assignment from cache before fetch even fails
@@ -754,6 +813,7 @@ describe('initialization options', () => {
         baseUrl: 'https://thisisabaddomainforthistest.com',
         assignmentLogger: mockLogger,
         useExpiredCache: true,
+        forceReinitialize: true,
       }),
     ).rejects.toThrow();
   });
@@ -854,6 +914,7 @@ describe('initialization options', () => {
         baseUrl,
         assignmentLogger: mockLogger,
         updateOnFetch,
+        forceReinitialize: true,
       });
 
       expect(fetchCallCount).toBe(1);
@@ -871,6 +932,7 @@ describe('initialization options', () => {
         assignmentLogger: mockLogger,
         updateOnFetch,
         useExpiredCache: true,
+        forceReinitialize: true,
       });
 
       // Should serve assignment from cache before fetch completes
@@ -900,6 +962,7 @@ describe('initialization options', () => {
         assignmentLogger: mockLogger,
         updateOnFetch,
         maxCacheAgeSeconds: fetchResolveDelayMs * 10,
+        forceReinitialize: true,
       });
 
       // No fetch will have been kicked off because of valid cache; previously fetched values will be served
@@ -942,6 +1005,7 @@ describe('initialization options', () => {
         apiKey,
         baseUrl,
         assignmentLogger: mockLogger,
+        forceReinitialize: true,
       });
     });
 
@@ -955,6 +1019,7 @@ describe('initialization options', () => {
         apiKey,
         baseUrl,
         assignmentLogger: mockLogger,
+        forceReinitialize: true,
       });
       expect(getInstance().getStringAssignment(flagKey, 'subject', {}, 'default-value')).toBe(
         'default-value',
diff --git a/src/index.ts b/src/index.ts
index bf192da..599ac6a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -113,6 +113,11 @@ export interface IClientConfig {
    * than the default storage provided by the SDK.
    */
   persistentStore?: IAsyncStore<Flag>;
+
+  /**
+   * Force reinitialize the SDK if it is already initialized.
+   */
+  forceReinitialize?: boolean;
 }
 
 export interface IClientConfigSync {
@@ -381,8 +386,23 @@ export async function init(config: IClientConfig): Promise<EppoClient> {
   validation.validateNotBlank(config.apiKey, 'API key required');
   let initializationError: Error | undefined;
   const instance = EppoJSClient.instance;
-  const { apiKey, persistentStore, baseUrl, maxCacheAgeSeconds, updateOnFetch } = config;
+  const { apiKey, persistentStore, baseUrl, maxCacheAgeSeconds, updateOnFetch, forceReinitialize } =
+    config;
   try {
+    if (EppoJSClient.initialized) {
+      if (forceReinitialize) {
+        applicationLogger.warn(
+          'Eppo SDK is already initialized, reinitializing since forceReinitialize is true.',
+        );
+        EppoJSClient.initialized = false;
+      } else {
+        applicationLogger.warn(
+          'Eppo SDK is already initialized, skipping reinitialization since forceReinitialize is false.',
+        );
+        return instance;
+      }
+    }
+
     // If any existing instances; ensure they are not polling
     instance.stopPolling();
     // Set up assignment logger and cache