diff --git a/packages/client-core/src/DataAdapterCore.ts b/packages/client-core/src/DataAdapterCore.ts
index 1d72a2b3..879486a8 100644
--- a/packages/client-core/src/DataAdapterCore.ts
+++ b/packages/client-core/src/DataAdapterCore.ts
@@ -6,7 +6,12 @@ import {
   DataSource,
 } from './StatsigDataAdapter';
 import { AnyStatsigOptions } from './StatsigOptionsCommon';
-import { StatsigUser, _getFullUserHash, _normalizeUser } from './StatsigUser';
+import {
+  StatsigUser,
+  StatsigUserInternal,
+  _getFullUserHash,
+  _normalizeUser,
+} from './StatsigUser';
 import {
   Storage,
   _getObjectFromStorage,
@@ -37,8 +42,9 @@ export abstract class DataAdapterCore {
   }
 
   getDataSync(user?: StatsigUser | undefined): DataAdapterResult | null {
-    const cacheKey = this._getCacheKey(user);
-    const inMem = this._inMemoryCache.get(cacheKey, user);
+    const normalized = user && _normalizeUser(user, this._options);
+    const cacheKey = this._getCacheKey(normalized);
+    const inMem = this._inMemoryCache.get(cacheKey, normalized);
 
     if (inMem) {
       return inMem;
@@ -47,14 +53,14 @@ export abstract class DataAdapterCore {
     const cache = this._loadFromCache(cacheKey);
     if (cache) {
       this._inMemoryCache.add(cacheKey, cache);
-      return this._inMemoryCache.get(cacheKey, user);
+      return this._inMemoryCache.get(cacheKey, normalized);
     }
 
     return null;
   }
 
   setData(data: string, user?: StatsigUser): void {
-    const normalized = user && _normalizeUser(user, this._options?.environment);
+    const normalized = user && _normalizeUser(user, this._options);
     const cacheKey = this._getCacheKey(normalized);
 
     this._inMemoryCache.add(
@@ -74,7 +80,7 @@ export abstract class DataAdapterCore {
 
   protected async _getDataAsyncImpl(
     current: DataAdapterResult | null,
-    user?: StatsigUser,
+    user?: StatsigUserInternal,
     options?: DataAdapterAsyncOptions,
   ): Promise<DataAdapterResult | null> {
     const cache = current ?? this.getDataSync(user);
@@ -97,8 +103,9 @@ export abstract class DataAdapterCore {
     user?: StatsigUser,
     options?: DataAdapterAsyncOptions,
   ): Promise<void> {
-    const cacheKey = this._getCacheKey(user);
-    const result = await this._getDataAsyncImpl(null, user, options);
+    const normalized = user && _normalizeUser(user, this._options);
+    const cacheKey = this._getCacheKey(normalized);
+    const result = await this._getDataAsyncImpl(null, normalized, options);
     if (result) {
       this._inMemoryCache.add(cacheKey, { ...result, source: 'Prefetch' });
     }
@@ -110,7 +117,7 @@ export abstract class DataAdapterCore {
     options?: DataAdapterAsyncOptions,
   ): Promise<string | null>;
 
-  protected abstract _getCacheKey(user?: StatsigUser): string;
+  protected abstract _getCacheKey(user?: StatsigUserInternal): string;
 
   protected abstract _isCachedResultValidFor204(
     result: DataAdapterResult,
@@ -119,7 +126,7 @@ export abstract class DataAdapterCore {
 
   private async _fetchAndPrepFromNetwork(
     cachedResult: DataAdapterResult | null,
-    user: StatsigUser | undefined,
+    user: StatsigUserInternal | undefined,
     options: DataAdapterAsyncOptions | undefined,
   ): Promise<DataAdapterResult | null> {
     let cachedData: string | null = null;
@@ -232,7 +239,7 @@ class InMemoryCache {
 
   get(
     cacheKey: string,
-    user: StatsigUser | undefined,
+    user: StatsigUserInternal | undefined,
   ): DataAdapterResult | null {
     const result = this._data[cacheKey];
     const cached = result?.stableID;
diff --git a/packages/client-core/src/EventLogger.ts b/packages/client-core/src/EventLogger.ts
index af156e26..135f7618 100644
--- a/packages/client-core/src/EventLogger.ts
+++ b/packages/client-core/src/EventLogger.ts
@@ -157,7 +157,7 @@ export class EventLogger {
       return true;
     }
 
-    const user = event.user ? event.user : {};
+    const user = event.user ? event.user : { statsigEnvironment: undefined };
     const metadata = event.metadata ? event.metadata : {};
     const key = [
       event.eventName,
diff --git a/packages/client-core/src/StatsigEvent.ts b/packages/client-core/src/StatsigEvent.ts
index ee7036af..8f0fc764 100644
--- a/packages/client-core/src/StatsigEvent.ts
+++ b/packages/client-core/src/StatsigEvent.ts
@@ -1,6 +1,6 @@
 import { EvaluationDetails, SecondaryExposure } from './EvaluationTypes';
 import { DynamicConfig, FeatureGate, Layer } from './StatsigTypes';
-import { StatsigUser } from './StatsigUser';
+import { StatsigUserInternal } from './StatsigUser';
 
 export type StatsigEvent = {
   eventName: string;
@@ -9,7 +9,7 @@ export type StatsigEvent = {
 };
 
 export type StatsigEventInternal = Omit<StatsigEvent, 'metadata'> & {
-  user: StatsigUser | null;
+  user: StatsigUserInternal | null;
   time: number;
   metadata?: { [key: string]: unknown } | null;
   secondaryExposures?: SecondaryExposure[];
@@ -21,7 +21,7 @@ const LAYER_EXPOSURE_NAME = 'statsig::layer_exposure';
 
 const _createExposure = (
   eventName: string,
-  user: StatsigUser,
+  user: StatsigUserInternal,
   details: EvaluationDetails,
   metadata: Record<string, string>,
   secondaryExposures: SecondaryExposure[],
@@ -43,7 +43,7 @@ export const _isExposureEvent = ({
 };
 
 export const _createGateExposure = (
-  user: StatsigUser,
+  user: StatsigUserInternal,
   gate: FeatureGate,
 ): StatsigEventInternal => {
   return _createExposure(
@@ -60,7 +60,7 @@ export const _createGateExposure = (
 };
 
 export const _createConfigExposure = (
-  user: StatsigUser,
+  user: StatsigUserInternal,
   config: DynamicConfig,
 ): StatsigEventInternal => {
   return _createExposure(
@@ -76,7 +76,7 @@ export const _createConfigExposure = (
 };
 
 export const _createLayerParameterExposure = (
-  user: StatsigUser,
+  user: StatsigUserInternal,
   layer: Layer,
   parameterName: string,
 ): StatsigEventInternal => {
diff --git a/packages/client-core/src/StatsigUser.ts b/packages/client-core/src/StatsigUser.ts
index cef5b742..fafd00e2 100644
--- a/packages/client-core/src/StatsigUser.ts
+++ b/packages/client-core/src/StatsigUser.ts
@@ -1,6 +1,9 @@
 import { _DJB2Object } from './Hashing';
 import { Log } from './Log';
-import type { StatsigEnvironment } from './StatsigOptionsCommon';
+import type {
+  AnyStatsigOptions,
+  StatsigEnvironment,
+} from './StatsigOptionsCommon';
 
 type StatsigUserPrimitives =
   | string
@@ -26,24 +29,24 @@ export type StatsigUser = {
 };
 
 export type StatsigUserInternal = StatsigUser & {
-  statsigEnvironment?: StatsigEnvironment;
+  statsigEnvironment: StatsigEnvironment | undefined;
 };
 
 export function _normalizeUser(
   original: StatsigUser,
-  environment?: StatsigEnvironment,
-): StatsigUser {
+  options?: AnyStatsigOptions | null,
+): StatsigUserInternal {
   try {
     const copy = JSON.parse(JSON.stringify(original)) as StatsigUserInternal;
 
-    if (environment != null) {
-      copy.statsigEnvironment = environment;
+    if (options != null && options.environment != null) {
+      copy.statsigEnvironment = options.environment;
     }
 
     return copy;
   } catch (error) {
     Log.error('Failed to JSON.stringify user');
-    return {};
+    return { statsigEnvironment: undefined };
   }
 }
 
diff --git a/packages/js-client/src/StatsigClient.ts b/packages/js-client/src/StatsigClient.ts
index 64c20db7..ccb81f5f 100644
--- a/packages/js-client/src/StatsigClient.ts
+++ b/packages/js-client/src/StatsigClient.ts
@@ -22,6 +22,7 @@ import {
   StatsigEvent,
   StatsigSession,
   StatsigUser,
+  StatsigUserInternal,
   _createConfigExposure,
   _createGateExposure,
   _createLayerParameterExposure,
@@ -48,7 +49,7 @@ export default class StatsigClient
   implements PrecomputedEvaluationsInterface
 {
   private _store: EvaluationStore;
-  private _user: StatsigUser;
+  private _user: StatsigUserInternal;
 
   /**
    * Retrieves an instance of the StatsigClient based on the provided SDK key.
@@ -97,7 +98,7 @@ export default class StatsigClient
     );
 
     this._store = new EvaluationStore();
-    this._user = user;
+    this._user = _normalizeUser(user, options);
   }
 
   /**
@@ -411,7 +412,7 @@ export default class StatsigClient
     this._logger.reset();
     this._store.reset();
 
-    this._user = _normalizeUser(user, this._options.environment);
+    this._user = _normalizeUser(user, this._options);
 
     const stableIdOverride = this._user.customIDs?.stableID;
     if (stableIdOverride) {
diff --git a/packages/js-client/src/StatsigEvaluationsDataAdapter.ts b/packages/js-client/src/StatsigEvaluationsDataAdapter.ts
index f7f5f37e..939309b4 100644
--- a/packages/js-client/src/StatsigEvaluationsDataAdapter.ts
+++ b/packages/js-client/src/StatsigEvaluationsDataAdapter.ts
@@ -7,8 +7,10 @@ import {
   InitializeResponse,
   Log,
   StatsigUser,
+  StatsigUserInternal,
   _getFullUserHash,
   _getStorageKey,
+  _normalizeUser,
   _typedJsonParse,
 } from '@statsig/client-core';
 
@@ -36,7 +38,11 @@ export class StatsigEvaluationsDataAdapter
     user: StatsigUser,
     options?: DataAdapterAsyncOptions,
   ): Promise<DataAdapterResult | null> {
-    return this._getDataAsyncImpl(current, user, options);
+    return this._getDataAsyncImpl(
+      current,
+      _normalizeUser(user, this._options),
+      options,
+    );
   }
 
   prefetchData(
@@ -78,7 +84,7 @@ export class StatsigEvaluationsDataAdapter
     return result ?? null;
   }
 
-  protected override _getCacheKey(user?: StatsigUser): string {
+  protected override _getCacheKey(user?: StatsigUserInternal): string {
     const key = _getStorageKey(
       this._getSdkKey(),
       user,
diff --git a/packages/js-client/src/__tests__/ClientAndEvironments.test.ts b/packages/js-client/src/__tests__/ClientAndEvironments.test.ts
new file mode 100644
index 00000000..dfa9dbbe
--- /dev/null
+++ b/packages/js-client/src/__tests__/ClientAndEvironments.test.ts
@@ -0,0 +1,92 @@
+import fetchMock from 'jest-fetch-mock';
+import { InitResponseString, MockLocalStorage } from 'statsig-test-helpers';
+
+import StatsigClient from '../StatsigClient';
+
+describe('StatsigClient and Environments', () => {
+  const user = { userID: 'a-user' };
+  const env = { statsigEnvironment: { tier: 'dev' } };
+  const expectedCacheKey = 'statsig.cached.evaluations.1769418430'; // DJB2(JSON({userID: 'a-user', statsigEnvironment: {tier: 'dev'}}))
+
+  let storageMock: MockLocalStorage;
+  let client: StatsigClient;
+
+  beforeAll(() => {
+    storageMock = MockLocalStorage.enabledMockStorage();
+    fetchMock.enableMocks();
+  });
+
+  afterAll(() => {
+    jest.clearAllMocks();
+    MockLocalStorage.disableMockStorage();
+  });
+
+  beforeEach(() => {
+    storageMock.clear();
+
+    fetchMock.mock.calls = [];
+    fetchMock.mockResponse(InitResponseString);
+
+    client = new StatsigClient('client-key', user, {
+      environment: { tier: 'dev' },
+      disableStatsigEncoding: true,
+    });
+  });
+
+  describe('When triggered by StatsigClient', () => {
+    it('sets the environment on post sync init requests', async () => {
+      client.initializeSync();
+      await new Promise((r) => setTimeout(r, 1));
+
+      const [, req] = fetchMock.mock.calls[0];
+      const body = JSON.parse(String(req?.body));
+
+      expect(body.user).toMatchObject(env);
+      expect(storageMock.data[expectedCacheKey]).toBeDefined();
+    });
+
+    it('sets the environment on async init requests', async () => {
+      await client.initializeAsync();
+
+      const [, req] = fetchMock.mock.calls[0];
+      const body = JSON.parse(String(req?.body));
+
+      expect(body.user).toMatchObject(env);
+      expect(storageMock.data[expectedCacheKey]).toBeDefined();
+    });
+  });
+
+  describe('When triggered by DataAdapter', () => {
+    it('sets the environment on prefetch requests', async () => {
+      await client.dataAdapter.prefetchData(user);
+
+      const [, req] = fetchMock.mock.calls[0];
+      const body = JSON.parse(String(req?.body));
+
+      expect(body.user).toMatchObject(env);
+      expect(storageMock.data[expectedCacheKey]).toBeDefined();
+    });
+
+    it('sets the environment on getDataAsync requests', async () => {
+      await client.dataAdapter.getDataAsync(null, user, {});
+
+      const [, req] = fetchMock.mock.calls[0];
+      const body = JSON.parse(String(req?.body));
+
+      expect(body.user).toMatchObject(env);
+      expect(storageMock.data[expectedCacheKey]).toBeDefined();
+    });
+  });
+
+  it('includes env on DataAdapter reads', () => {
+    storageMock.data[expectedCacheKey] = JSON.stringify({
+      source: 'Network',
+      receivedAt: Date.now(),
+      data: InitResponseString,
+      stableID: null,
+      fullUserHash: null,
+    });
+
+    expect(client.dataAdapter.getDataSync(user)).toBeDefined();
+  });
+});
diff --git a/packages/js-on-device-eval-client/src/StatsigOnDeviceEvalClient.ts b/packages/js-on-device-eval-client/src/StatsigOnDeviceEvalClient.ts
index 596eaee1..7b4ecc75 100644
--- a/packages/js-on-device-eval-client/src/StatsigOnDeviceEvalClient.ts
+++ b/packages/js-on-device-eval-client/src/StatsigOnDeviceEvalClient.ts
@@ -148,12 +148,15 @@ export default class StatsigOnDeviceEvalClient
     user: StatsigUser,
     options?: FeatureGateEvaluationOptions,
   ): FeatureGate {
-    user = _normalizeUser(user, this._options.environment);
-    const { evaluation, details } = this._evaluator.evaluateGate(name, user);
+    const normalized = _normalizeUser(user, this._options);
+    const { evaluation, details } = this._evaluator.evaluateGate(
+      name,
+      normalized,
+    );
 
     const gate = _makeFeatureGate(name, details, evaluation);
 
-    this._enqueueExposure(name, _createGateExposure(user, gate), options);
+    this._enqueueExposure(name, _createGateExposure(normalized, gate), options);
 
     this.$emt({ name: 'gate_evaluation', gate });
 
@@ -165,18 +168,25 @@ export default class StatsigOnDeviceEvalClient
     user: StatsigUser,
     options?: DynamicConfigEvaluationOptions,
   ): DynamicConfig {
-    user = _normalizeUser(user, this._options.environment);
-    const { evaluation, details } = this._evaluator.evaluateConfig(name, user);
+    const normalized = _normalizeUser(user, this._options);
+    const { evaluation, details } = this._evaluator.evaluateConfig(
+      name,
+      normalized,
+    );
 
     const config = _makeDynamicConfig(name, details, evaluation);
     const overridden = this._overrideAdapter?.getDynamicConfigOverride?.(
       config,
-      user,
+      normalized,
       options,
     );
 
     const result = overridden ?? config;
-    this._enqueueExposure(name, _createConfigExposure(user, result), options);
+    this._enqueueExposure(
+      name,
+      _createConfigExposure(normalized, result),
+      options,
+    );
     this.$emt({ name: 'dynamic_config_evaluation', dynamicConfig: result });
     return result;
   }
@@ -186,18 +196,25 @@ export default class StatsigOnDeviceEvalClient
     user: StatsigUser,
     options?: ExperimentEvaluationOptions,
   ): Experiment {
-    user = _normalizeUser(user, this._options.environment);
-    const { evaluation, details } = this._evaluator.evaluateConfig(name, user);
+    const normalized = _normalizeUser(user, this._options);
+    const { evaluation, details } = this._evaluator.evaluateConfig(
+      name,
+      normalized,
+    );
 
     const experiment = _makeExperiment(name, details, evaluation);
     const overridden = this._overrideAdapter?.getExperimentOverride?.(
       experiment,
-      user,
+      normalized,
       options,
     );
 
     const result = overridden ?? experiment;
-    this._enqueueExposure(name, _createConfigExposure(user, result), options);
+    this._enqueueExposure(
+      name,
+      _createConfigExposure(normalized, result),
+      options,
+    );
     this.$emt({ name: 'experiment_evaluation', experiment: result });
     return result;
   }
@@ -207,13 +224,16 @@ export default class StatsigOnDeviceEvalClient
     user: StatsigUser,
     options?: LayerEvaluationOptions,
   ): Layer {
-    user = _normalizeUser(user, this._options.environment);
-    const { evaluation, details } = this._evaluator.evaluateLayer(name, user);
+    const normalized = _normalizeUser(user, this._options);
+    const { evaluation, details } = this._evaluator.evaluateLayer(
+      name,
+      normalized,
+    );
 
     const layer = _makeLayer(name, details, evaluation, (param: string) => {
       this._enqueueExposure(
         name,
-        _createLayerParameterExposure(user, layer, param),
+        _createLayerParameterExposure(normalized, layer, param),
         options,
       );
     });
@@ -238,7 +258,11 @@ export default class StatsigOnDeviceEvalClient
           }
         : eventOrName;
 
-    this._logger.enqueue({ ...event, user, time: Date.now() });
+    this._logger.enqueue({
+      ...event,
+      user: _normalizeUser(user, this._options),
+      time: Date.now(),
+    });
   }
 
   protected override _primeReadyRipcord(): void {