diff --git a/index.test.ts b/index.test.ts
index 1679e3b..69ef0ee 100644
--- a/index.test.ts
+++ b/index.test.ts
@@ -77,6 +77,72 @@ describe("createRocketflagClient", () => {
       expect(flag).toEqual(mockFlag);
     });
 
+    it("should fetch a flag with env in the user context", async () => {
+      const mockFlag: FlagStatus = { name: "Test Flag", enabled: true, id: flagId };
+      (fetch as jest.Mock).mockResolvedValue({ ok: true, json: () => Promise.resolve(mockFlag) });
+
+      const client = createRocketflagClient();
+      const flag = await client.getFlag(flagId, { env: "staging" });
+
+      expect(fetch).toHaveBeenCalledTimes(1);
+
+      const expectedUrl = `${apiUrl}/v1/flags/${flagId}?env=staging`;
+      const expectedURLObject = new URL(expectedUrl);
+
+      expect(fetch).toHaveBeenCalledWith(expect.objectContaining({ href: expectedURLObject.href }), { method: "GET" });
+      expect(flag).toEqual(mockFlag);
+    });
+
+    it("should fetch a flag with cohort and env in the user context", async () => {
+      const mockFlag: FlagStatus = { name: "Test Flag", enabled: true, id: flagId };
+      (fetch as jest.Mock).mockResolvedValue({ ok: true, json: () => Promise.resolve(mockFlag) });
+
+      const client = createRocketflagClient();
+      const flag = await client.getFlag(flagId, { cohort: "user123", env: "staging" });
+
+      expect(fetch).toHaveBeenCalledTimes(1);
+
+      const expectedUrl = `${apiUrl}/v1/flags/${flagId}?cohort=user123&env=staging`;
+      const expectedURLObject = new URL(expectedUrl);
+
+      expect(fetch).toHaveBeenCalledWith(expect.objectContaining({ href: expectedURLObject.href }), { method: "GET" });
+      expect(flag).toEqual(mockFlag);
+    });
+
+    describe("userContext validation", () => {
+      it.each([
+        { value: "staging", shouldThrow: false },
+        { value: "123", shouldThrow: false },
+        { value: "production1", shouldThrow: false },
+        { value: "test2", shouldThrow: false },
+        { value: "staging test", shouldThrow: true },
+        { value: "staging-test", shouldThrow: true },
+        { value: "staging!", shouldThrow: true },
+        { value: "staging@test", shouldThrow: true },
+        { value: "staging+test@rocketflag.com", shouldThrow: true },
+      ])("should handle env value: $value", async ({ value, shouldThrow }) => {
+        const client = createRocketflagClient();
+
+        if (shouldThrow) {
+          await expect(client.getFlag(flagId, { env: value })).rejects.toThrow(
+            "env values must be alphanumeric. Invalid value for env: env",
+          );
+        } else {
+          const mockFlag: FlagStatus = { name: "Test Flag", enabled: true, id: flagId };
+          (fetch as jest.Mock).mockResolvedValue({ ok: true, json: () => Promise.resolve(mockFlag) });
+          await expect(client.getFlag(flagId, { env: value })).resolves.toEqual(mockFlag);
+        }
+      });
+    });
+
+    it("should throw an error if env in userContext contains invalid values", async () => {
+      const client = createRocketflagClient();
+      const invalidUserContext = { env: { a: 1 } };
+      await expect(client.getFlag(flagId, invalidUserContext as unknown as UserContext)).rejects.toThrow(
+        "userContext values must be of type string, number, or boolean. Invalid value for key: env",
+      );
+    });
+
     it("should throw an APIError on non-ok response with correct status and statusText", async () => {
       (fetch as jest.Mock).mockResolvedValue({
         ok: false,
@@ -126,7 +192,7 @@ describe("createRocketflagClient", () => {
       const client = createRocketflagClient();
       const invalidUserContext = { cohort: { a: 1 } };
       await expect(client.getFlag(flagId, invalidUserContext as unknown as UserContext)).rejects.toThrow(
-        "userContext values must be of type string, number, or boolean. Invalid value for key: cohort"
+        "userContext values must be of type string, number, or boolean. Invalid value for key: cohort",
       );
     });
 
diff --git a/index.ts b/index.ts
index 0de535b..f25a752 100644
--- a/index.ts
+++ b/index.ts
@@ -4,6 +4,7 @@ import { validateFlag } from "./validateFlag";
 const GET_METHOD = "GET";
 const DEFAULT_API_URL = "https://api.rocketflag.app";
 const DEFAULT_VERSION = "v1";
+const ALPHANUMERIC_REGEX = /^[a-zA-Z0-9]+$/;
 
 export type FlagStatus = {
   name: string;
@@ -13,6 +14,7 @@ export type FlagStatus = {
 
 export interface UserContext {
   cohort?: string | number | boolean;
+  env?: string;
 }
 
 export interface RocketFlagClient {
@@ -36,6 +38,9 @@ const createRocketflagClient = (version = DEFAULT_VERSION, apiUrl = DEFAULT_API_
       if (typeof value !== "string" && typeof value !== "number" && typeof value !== "boolean") {
         throw new Error(`userContext values must be of type string, number, or boolean. Invalid value for key: ${key}`);
       }
+      if (key === "env" && (typeof value !== "string" || !ALPHANUMERIC_REGEX.test(value))) {
+        throw new Error(`env values must be alphanumeric. Invalid value for env: ${[key]}`);
+      }
     }
 
     const url = new URL(`${apiUrl}/${version}/flags/${flagId}`);
diff --git a/package.json b/package.json
index 2a13293..313e426 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@rocketflag/node-sdk",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "author": "RocketFlag Developers (https://rocketflag.app)",
   "main": "index.js",
   "scripts": {