diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2af3579f897..ccbbe7fac65 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,8 +6,10 @@ The version headers in this history reflect the versions of Apollo Server itself
 - [__CHANGELOG for `@apollo/federation`__](https://github.com/apollographql/apollo-server/blob/master/packages/apollo-federation/CHANGELOG.md)
 
 ### vNEXT
+
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.
 
+- `apollo-engine-reporting`: Deprecate the `ENGINE_API_KEY` environment variable in favor of its new name, `APOLLO_KEY`.  Continued use of `ENGINE_API_KEY` will result in deprecation warnings and support for it will be removed in a future major version. [#3923](https://github.com/apollographql/apollo-server/pull/3923)
 - `apollo-engine-reporting`: Deprecated the `APOLLO_SCHEMA_TAG` environment variable in favor of its new name, `APOLLO_GRAPH_VARIANT`.  Similarly, within the `engine` configuration object, the `schemaTag` property has been renamed `graphVariant`.  The functionality remains otherwise unchanged, but their new names mirror the name used within Apollo Graph Manager.  Continued use of the now-deprecated names will result in deprecation warnings and support will be dropped completely in the next "major" update.  To avoid misconfiguration, a runtime error will be thrown if _both_ new and deprecated names are set. [PR #3855](https://github.com/apollographql/apollo-server/pull/3855)
 - Allow passing a `WebSocket.Server` to `ApolloServer.installSubscriptionHandlers`. [PR #2314](https://github.com/apollographql/apollo-server/pull/2314)
 
diff --git a/package-lock.json b/package-lock.json
index 4ea93fcb910..c6976be992c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -6391,6 +6391,7 @@
       "version": "file:packages/apollo-server-cloud-functions",
       "requires": {
         "@apollographql/graphql-playground-html": "1.6.24",
+        "apollo-engine-reporting": "file:packages/apollo-engine-reporting",
         "apollo-server-core": "file:packages/apollo-server-core",
         "apollo-server-env": "file:packages/apollo-server-env",
         "apollo-server-types": "file:packages/apollo-server-types",
diff --git a/packages/apollo-engine-reporting/src/agent.ts b/packages/apollo-engine-reporting/src/agent.ts
index 75a3d285711..dcac41dddfe 100644
--- a/packages/apollo-engine-reporting/src/agent.ts
+++ b/packages/apollo-engine-reporting/src/agent.ts
@@ -16,6 +16,8 @@ import { GraphQLRequestContext, Logger } from 'apollo-server-types';
 import { InMemoryLRUCache } from 'apollo-server-caching';
 import { defaultEngineReportingSignature } from 'apollo-graphql';
 
+let warnedOnDeprecatedApiKey = false;
+
 export interface ClientInfo {
   clientName?: string;
   clientVersion?: string;
@@ -45,7 +47,30 @@ export type GenerateClientInfo<TContext> = (
   requestContext: GraphQLRequestContext<TContext>,
 ) => ClientInfo;
 
-// AS3: Drop support for deprecated bits.
+// AS3: Drop support for deprecated `ENGINE_API_KEY`.
+export function getEngineApiKey(
+  {engine, skipWarn = false, logger= console }:
+    {engine: EngineReportingOptions<any> | boolean | undefined, skipWarn?: boolean, logger?: Logger }
+    ) {
+  if (typeof engine === 'object') {
+    if (engine.apiKey) {
+      return engine.apiKey;
+    }
+  }
+  const legacyApiKeyFromEnv = process.env.ENGINE_API_KEY;
+  const apiKeyFromEnv = process.env.APOLLO_KEY;
+
+  if(legacyApiKeyFromEnv && apiKeyFromEnv && !skipWarn) {
+    logger.warn(`Both ENGINE_API_KEY (deprecated) and APOLLO_KEY are set; defaulting to APOLLO_KEY.`);
+  }
+  if(legacyApiKeyFromEnv && !warnedOnDeprecatedApiKey && !skipWarn) {
+    logger.warn(`[deprecated] Setting the key via ENGINE_API_KEY is deprecated and will not be supported in future versions.`);
+    warnedOnDeprecatedApiKey = true;
+  }
+  return  apiKeyFromEnv || legacyApiKeyFromEnv || ''
+}
+
+// AS3: Drop support for deprecated `ENGINE_SCHEMA_TAG`.
 export function getEngineGraphVariant(engine: EngineReportingOptions<any> | boolean | undefined, logger: Logger = console): string | undefined {
   if (engine === false) {
     return;
@@ -242,9 +267,9 @@ const serviceHeaderDefaults = {
 // EngineReportingExtensions for each request and sends batches of trace reports
 // to the Engine server.
 export class EngineReportingAgent<TContext = any> {
-  private options: EngineReportingOptions<TContext>;
+  private readonly options: EngineReportingOptions<TContext>;
+  private readonly apiKey: string;
   private logger: Logger = console;
-  private apiKey: string;
   private graphVariant: string;
   private reports: { [schemaHash: string]: FullTracesReport } = Object.create(
     null,
@@ -262,12 +287,12 @@ export class EngineReportingAgent<TContext = any> {
 
   public constructor(options: EngineReportingOptions<TContext> = {}) {
     this.options = options;
+    this.apiKey = getEngineApiKey({engine: this.options, skipWarn: false, logger: this.logger});
     if (options.logger) this.logger = options.logger;
-    this.apiKey = options.apiKey || process.env.ENGINE_API_KEY || '';
     this.graphVariant = getEngineGraphVariant(options, this.logger) || '';
     if (!this.apiKey) {
       throw new Error(
-        'To use EngineReportingAgent, you must specify an API key via the apiKey option or the ENGINE_API_KEY environment variable.',
+        `To use EngineReportingAgent, you must specify an API key via the apiKey option or the APOLLO_KEY environment variable.`,
       );
     }
 
diff --git a/packages/apollo-gateway/CHANGELOG.md b/packages/apollo-gateway/CHANGELOG.md
index e6f2dbfd589..bce2b5e9103 100644
--- a/packages/apollo-gateway/CHANGELOG.md
+++ b/packages/apollo-gateway/CHANGELOG.md
@@ -4,7 +4,8 @@
 
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.
 
-- Deprecated the `APOLLO_SCHEMA_TAG` environment variable in favor of its new name, `APOLLO_GRAPH_VARIANT`.  The functionality remains otherwise identical, but the new name mirrors the name used within Apollo Graph Manager.  Use of the now-deprecated name will result in a deprecation warning and support will be dropped completely in a future "major" update.  To avoid misconfiguration, runtime errors will be thrown if the new and deprecated name are _both_ set. [#3855](https://github.com/apollographql/apollo-server/pull/3855)
+- Deprecated the `ENGINE_API_KEY` environment variable in favor of its new name, `APOLLO_KEY`.  Continued use of `ENGINE_API_KEY` will result in deprecation warnings being printed to the server console.  Support for `ENGINE_API_KEY` will be removed in a future, major update.  [#3923](https://github.com/apollographql/apollo-server/pull/3923)
+- Deprecated the `APOLLO_SCHEMA_TAG` environment variable in favor of its new name, `APOLLO_GRAPH_VARIANT`.  The functionality remains otherwise identical, but the new name mirrors the name used within Apollo Graph Manager.  Use of the now-deprecated name will result in a deprecation warning being printed to the server console.  Support will be removed entirely in a future, major update.  To avoid misconfiguration, runtime errors will be thrown if the new and deprecated name are _both_ set. [#3855](https://github.com/apollographql/apollo-server/pull/3855)
 - Cache stringified representations of downstream query bodies within the query plan to address performance implications incurred by repeatedly `print`ing the same`DocumentNode`s with the `graphql` printer.  This improvement is more pronounced on larger documents.  [PR #4018](https://github.com/apollographql/apollo-server/pull/4018)
 - Add inadvertently excluded `apollo-server-errors` runtime dependency. [#3927](https://github.com/apollographql/apollo-server/pull/3927)
 
@@ -29,6 +30,7 @@
 - Implement retry logic for requests to GCS [PR #3836](https://github.com/apollographql/apollo-server/pull/3836) Note: coupled with this change is a small alteration in how the gateway polls GCS for updates in managed mode. Previously, the tick was on a specific interval. Now, every tick starts after the round of fetches to GCS completes. For more details, see the linked PR.
 - Gateway issues health checks to downstream services via `serviceHealthCheck` configuration option. Note: expected behavior differs between managed and unmanaged federation. See PR for new test cases and documentation. [#3930](https://github.com/apollographql/apollo-server/pull/3930)
 
+
 ## 0.13.2
 
 - __BREAKING__: The behavior and signature of `RemoteGraphQLDataSource`'s `didReceiveResponse` method has been changed.  No changes are necessary _unless_ your implementation has overridden the default behavior of this method by either extending the class and overriding the method or by providing `didReceiveResponse` as a parameter to the `RemoteGraphQLDataSource`'s constructor options.  Implementations which have provided their own `didReceiveResponse` using either of these methods should view the PR linked here for details on what has changed.  [PR #3743](https://github.com/apollographql/apollo-server/pull/3743)
diff --git a/packages/apollo-server-core/src/ApolloServer.ts b/packages/apollo-server-core/src/ApolloServer.ts
index 67872846dfa..f5de66b3c20 100644
--- a/packages/apollo-server-core/src/ApolloServer.ts
+++ b/packages/apollo-server-core/src/ApolloServer.ts
@@ -71,7 +71,7 @@ import {
 
 import { Headers } from 'apollo-server-env';
 import { buildServiceDefinition } from '@apollographql/apollo-tools';
-import {getEngineGraphVariant} from "apollo-engine-reporting/dist/agent";
+import { getEngineApiKey, getEngineGraphVariant } from "apollo-engine-reporting/dist/agent";
 import { Logger } from "apollo-server-types";
 
 const NoIntrospection = (context: ValidationContext) => ({
@@ -87,20 +87,8 @@ const NoIntrospection = (context: ValidationContext) => ({
   },
 });
 
-function getEngineApiKey(engine: Config['engine']): string | undefined {
-  const keyFromEnv = process.env.ENGINE_API_KEY || '';
-  if (engine === false) {
-    return;
-  } else if (typeof engine === 'object' && engine.apiKey) {
-    return engine.apiKey;
-  } else if (keyFromEnv) {
-    return keyFromEnv;
-  }
-  return;
-}
-
-function getEngineServiceId(engine: Config['engine']): string | undefined {
-  const engineApiKey = getEngineApiKey(engine);
+function getEngineServiceId(engine: Config['engine'], logger: Logger): string | undefined {
+  const engineApiKey = getEngineApiKey({engine, skipWarn: true, logger} );
   if (engineApiKey) {
     return engineApiKey.split(':', 2)[1];
   }
@@ -330,8 +318,8 @@ export class ApolloServerBase {
     // service ID from the API key for plugins which only needs service ID.
     // The truthiness of this value can also be used in other forks of logic
     // related to Engine, as is the case with EngineReportingAgent just below.
-    this.engineServiceId = getEngineServiceId(engine);
-    const apiKey = getEngineApiKey(engine);
+    this.engineServiceId = getEngineServiceId(engine, this.logger);
+    const apiKey = getEngineApiKey({engine, skipWarn: true, logger: this.logger});
     if (apiKey) {
       this.engineApiKeyHash = createSHA('sha512')
         .update(apiKey)
diff --git a/packages/apollo-server-core/src/__tests__/ApolloServerBase.test.ts b/packages/apollo-server-core/src/__tests__/ApolloServerBase.test.ts
index fc6440092cc..52013e02fe6 100644
--- a/packages/apollo-server-core/src/__tests__/ApolloServerBase.test.ts
+++ b/packages/apollo-server-core/src/__tests__/ApolloServerBase.test.ts
@@ -94,3 +94,50 @@ describe('ApolloServerBase construction', () => {
     );
   });
 });
+
+describe('environment variables', () => {
+  const OLD_ENV = process.env;
+
+  beforeEach(() => {
+    jest.resetModules();
+    process.env = { ...OLD_ENV };
+    delete process.env.ENGINE_API_KEY;
+    delete process.env.APOLLO_KEY;
+  });
+
+  afterEach(() => {
+    process.env = OLD_ENV;
+  });
+
+  it('constructs a reporting agent with the ENGINE_API_KEY (deprecated) environment variable and warns', async () => {
+    // set the variables
+    process.env.ENGINE_API_KEY = 'just:fake:stuff';
+    const spyConsoleWarn = jest.spyOn(console, 'warn').mockImplementation();
+
+    const server = new ApolloServerBase({
+      typeDefs,
+      resolvers
+    });
+
+    await server.stop();
+    expect(spyConsoleWarn).toHaveBeenCalledTimes(1);
+    spyConsoleWarn.mockReset();
+  });
+
+  it('warns with both the legacy env var and new env var set', async () => {
+    // set the variables
+    process.env.ENGINE_API_KEY = 'just:fake:stuff';
+    process.env.APOLLO_KEY = 'also:fake:stuff';
+    const spyConsoleWarn = jest.spyOn(console, 'warn').mockImplementation();
+
+    const server = new ApolloServerBase({
+      typeDefs,
+      resolvers
+    });
+
+    await server.stop();
+    // Once for deprecation, once for double-set
+    expect(spyConsoleWarn).toHaveBeenCalledTimes(2);
+    spyConsoleWarn.mockReset();
+  });
+});