diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8563a5a5c09..3ea42ff5e21 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 **Note:** This is a cumulative changelog that outlines all of the Apollo Client project child package changes that were bundled into a specific `apollo-client` release.
 
+## Apollo Client vNEXT
+
+### Apollo Cache In-Memory
+
+- Support `new InMemoryCache({ freezeResults: true })` to help enforce immutability. <br/>
+  [@benjamn](https://github.com/benjamn) in [#4514](https://github.com/apollographql/apollo-client/pull/4514)
+
 ## Apollo Client 2.5.1
 
 ### apollo-client 2.5.1
diff --git a/package.json b/package.json
index 0b6e23580df..5a610388858 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
     {
       "name": "apollo-cache-inmemory",
       "path": "./packages/apollo-cache-inmemory/lib/bundle.cjs.min.js",
-      "maxSize": "4.9 kB"
+      "maxSize": "4.95 kB"
     },
     {
       "name": "apollo-client",
diff --git a/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/cache.ts.snap b/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/cache.ts.snap
index 0cd8b06df71..d972da111c5 100644
--- a/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/cache.ts.snap
+++ b/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/cache.ts.snap
@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/2) 1`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/3) 1`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -17,7 +17,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/2) 2`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/3) 2`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -38,7 +38,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/2) 3`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/3) 3`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -59,7 +59,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/2) 4`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/3) 4`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -80,7 +80,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/2) 5`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/3) 5`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -101,7 +101,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/2) 6`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (1/3) 6`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -122,7 +122,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/2) 1`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/3) 1`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -139,7 +139,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/2) 2`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/3) 2`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -160,7 +160,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/2) 3`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/3) 3`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -181,7 +181,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/2) 4`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/3) 4`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -202,7 +202,7 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/2) 5`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/3) 5`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -223,7 +223,129 @@ Object {
 }
 `;
 
-exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/2) 6`] = `
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (2/3) 6`] = `
+Object {
+  "bar": Object {
+    "i": 10,
+    "j": 11,
+    "k": 12,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": "Bar",
+    },
+  },
+}
+`;
+
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (3/3) 1`] = `
+Object {
+  "bar": Object {
+    "i": 7,
+  },
+  "foo": Object {
+    "e": 4,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (3/3) 2`] = `
+Object {
+  "bar": Object {
+    "i": 7,
+    "j": 8,
+    "k": 9,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (3/3) 3`] = `
+Object {
+  "bar": Object {
+    "i": 10,
+    "j": 8,
+    "k": 9,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (3/3) 4`] = `
+Object {
+  "bar": Object {
+    "i": 10,
+    "j": 11,
+    "k": 12,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (3/3) 5`] = `
+Object {
+  "bar": Object {
+    "i": 7,
+    "j": 8,
+    "k": 9,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": "Bar",
+    },
+  },
+}
+`;
+
+exports[`Cache writeFragment will write some deeply nested data into the store at any id (3/3) 6`] = `
 Object {
   "bar": Object {
     "i": 10,
diff --git a/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/mapCache.ts.snap b/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/mapCache.ts.snap
index c3711026b09..4682281f7f0 100644
--- a/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/mapCache.ts.snap
+++ b/packages/apollo-cache-inmemory/src/__tests__/__snapshots__/mapCache.ts.snap
@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/2) 1`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/3) 1`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -17,7 +17,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/2) 2`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/3) 2`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -38,7 +38,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/2) 3`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/3) 3`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -59,7 +59,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/2) 4`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/3) 4`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -80,7 +80,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/2) 5`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/3) 5`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -101,7 +101,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/2) 6`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (1/3) 6`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -122,7 +122,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/2) 1`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/3) 1`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -139,7 +139,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/2) 2`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/3) 2`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -160,7 +160,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/2) 3`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/3) 3`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -181,7 +181,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/2) 4`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/3) 4`] = `
 Object {
   "bar": Object {
     "i": 10,
@@ -202,7 +202,7 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/2) 5`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/3) 5`] = `
 Object {
   "bar": Object {
     "i": 7,
@@ -223,7 +223,129 @@ Object {
 }
 `;
 
-exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/2) 6`] = `
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (2/3) 6`] = `
+Object {
+  "bar": Object {
+    "i": 10,
+    "j": 11,
+    "k": 12,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": "Bar",
+    },
+  },
+}
+`;
+
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (3/3) 1`] = `
+Object {
+  "bar": Object {
+    "i": 7,
+  },
+  "foo": Object {
+    "e": 4,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (3/3) 2`] = `
+Object {
+  "bar": Object {
+    "i": 7,
+    "j": 8,
+    "k": 9,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (3/3) 3`] = `
+Object {
+  "bar": Object {
+    "i": 10,
+    "j": 8,
+    "k": 9,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (3/3) 4`] = `
+Object {
+  "bar": Object {
+    "i": 10,
+    "j": 11,
+    "k": 12,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": undefined,
+    },
+  },
+}
+`;
+
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (3/3) 5`] = `
+Object {
+  "bar": Object {
+    "i": 7,
+    "j": 8,
+    "k": 9,
+  },
+  "foo": Object {
+    "e": 4,
+    "f": 5,
+    "g": 6,
+    "h": Object {
+      "generated": false,
+      "id": "bar",
+      "type": "id",
+      "typename": "Bar",
+    },
+  },
+}
+`;
+
+exports[`MapCache Cache writeFragment will write some deeply nested data into the store at any id (3/3) 6`] = `
 Object {
   "bar": Object {
     "i": 10,
diff --git a/packages/apollo-cache-inmemory/src/__tests__/cache.ts b/packages/apollo-cache-inmemory/src/__tests__/cache.ts
index f0cb6e27ed1..58e89177908 100644
--- a/packages/apollo-cache-inmemory/src/__tests__/cache.ts
+++ b/packages/apollo-cache-inmemory/src/__tests__/cache.ts
@@ -25,6 +25,12 @@ describe('Cache', () => {
           resultCaching: false,
         }).restore(cloneDeep(data))
       ),
+      initialDataForCaches.map(
+        data => new InMemoryCache({
+          addTypename: false,
+          freezeResults: true,
+        }).restore(cloneDeep(data))
+      ),
     ];
 
     cachesList.forEach((caches, i) => {
@@ -48,6 +54,11 @@ describe('Cache', () => {
         ...config,
         resultCaching: false,
       }),
+      new InMemoryCache({
+        addTypename: false,
+        ...config,
+        freezeResults: true,
+      }),
     ];
 
     caches.forEach((cache, i) => {
diff --git a/packages/apollo-cache-inmemory/src/__tests__/roundtrip.ts b/packages/apollo-cache-inmemory/src/__tests__/roundtrip.ts
index ad4a337c711..30a70ae8914 100644
--- a/packages/apollo-cache-inmemory/src/__tests__/roundtrip.ts
+++ b/packages/apollo-cache-inmemory/src/__tests__/roundtrip.ts
@@ -16,8 +16,25 @@ import {
 
 const fragmentMatcherFunction = new HeuristicFragmentMatcher().match;
 
+function assertDeeplyFrozen(value: any, stack: any[] = []) {
+  if (
+    value !== null &&
+    typeof value === 'object' &&
+    stack.indexOf(value) < 0
+  ) {
+    expect(Object.isExtensible(value)).toBe(false);
+    expect(Object.isFrozen(value)).toBe(true);
+    stack.push(value);
+    Object.keys(value).forEach(key => {
+      assertDeeplyFrozen(value[key], stack);
+    });
+    expect(stack.pop()).toBe(value);
+  }
+}
+
 function storeRoundtrip(query: DocumentNode, result: any, variables = {}) {
   const reader = new StoreReader();
+  const immutableReader = new StoreReader({ freezeResults: true });
   const writer = new StoreWriter();
 
   const store = writer.writeQueryToStore({
@@ -41,6 +58,22 @@ function storeRoundtrip(query: DocumentNode, result: any, variables = {}) {
   expect(store).toBeInstanceOf(DepTrackingCache);
   expect(reader.readQueryFromStore(readOptions)).toBe(reconstructedResult);
 
+  const immutableResult = immutableReader.readQueryFromStore(readOptions);
+  expect(immutableResult).toEqual(reconstructedResult);
+  expect(immutableReader.readQueryFromStore(readOptions)).toBe(immutableResult);
+  if (process.env.NODE_ENV !== 'production') {
+    try {
+      // Note: this illegal assignment will only throw in strict mode, but that's
+      // safe to assume because this test file is a module.
+      (immutableResult as any).illegal = "this should not work";
+      throw new Error("unreached");
+    } catch (e) {
+      expect(e.message).not.toMatch(/unreached/);
+      expect(e).toBeInstanceOf(TypeError);
+    }
+    assertDeeplyFrozen(immutableResult);
+  }
+
   // Now make sure subtrees of the result are identical even after we write
   // an additional bogus field to the store.
   writer.writeQueryToStore({
@@ -203,6 +236,19 @@ describe('roundtrip', () => {
   });
 
   it('with GraphQLJSON scalar type', () => {
+    const updateClub = {
+      uid: '1d7f836018fc11e68d809dfee940f657',
+      name: 'Eple',
+      settings: {
+        name: 'eple',
+        currency: 'AFN',
+        calendarStretch: 2,
+        defaultPreAllocationPeriod: 1,
+        confirmationEmailCopy: null,
+        emailDomains: null,
+      },
+    };
+
     storeRoundtrip(
       gql`
         {
@@ -214,20 +260,14 @@ describe('roundtrip', () => {
         }
       `,
       {
-        updateClub: {
-          uid: '1d7f836018fc11e68d809dfee940f657',
-          name: 'Eple',
-          settings: {
-            name: 'eple',
-            currency: 'AFN',
-            calendarStretch: 2,
-            defaultPreAllocationPeriod: 1,
-            confirmationEmailCopy: null,
-            emailDomains: null,
-          },
-        },
+        updateClub,
       },
     );
+
+    // Just because we read from the store using { freezeResults: true }, the
+    // original data should not be frozen.
+    expect(Object.isExtensible(updateClub)).toBe(true);
+    expect(Object.isFrozen(updateClub)).toBe(false);
   });
 
   describe('directives', () => {
diff --git a/packages/apollo-cache-inmemory/src/inMemoryCache.ts b/packages/apollo-cache-inmemory/src/inMemoryCache.ts
index 3d4af3f4f4a..85e3ba0088e 100644
--- a/packages/apollo-cache-inmemory/src/inMemoryCache.ts
+++ b/packages/apollo-cache-inmemory/src/inMemoryCache.ts
@@ -26,6 +26,7 @@ import { ObjectCache } from './objectCache';
 
 export interface InMemoryCacheConfig extends ApolloReducerConfig {
   resultCaching?: boolean;
+  freezeResults?: boolean;
 }
 
 const defaultConfig: InMemoryCacheConfig = {
@@ -33,6 +34,7 @@ const defaultConfig: InMemoryCacheConfig = {
   dataIdFromObject: defaultDataIdFromObject,
   addTypename: true,
   resultCaching: true,
+  freezeResults: false,
 };
 
 export function defaultDataIdFromObject(result: any): string | null {
@@ -128,8 +130,11 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
     // original this.data cache object.
     this.optimisticData = this.data;
 
-    this.storeReader = new StoreReader(this.cacheKeyRoot);
     this.storeWriter = new StoreWriter();
+    this.storeReader = new StoreReader({
+      cacheKeyRoot: this.cacheKeyRoot,
+      freezeResults: config.freezeResults,
+    });
 
     const cache = this;
     const { maybeBroadcastWatch } = cache;
diff --git a/packages/apollo-cache-inmemory/src/readFromStore.ts b/packages/apollo-cache-inmemory/src/readFromStore.ts
index 495b120a1c8..01b14678778 100644
--- a/packages/apollo-cache-inmemory/src/readFromStore.ts
+++ b/packages/apollo-cache-inmemory/src/readFromStore.ts
@@ -21,6 +21,7 @@ import {
   shouldInclude,
   toIdValue,
   mergeDeepArray,
+  maybeDeepFreeze,
 } from 'apollo-utilities';
 
 import { Cache } from 'apollo-cache';
@@ -93,15 +94,24 @@ type ExecSelectionSetOptions = {
   execContext: ExecContext;
 };
 
+export interface StoreReaderConfig {
+  cacheKeyRoot?: CacheKeyNode;
+  freezeResults?: boolean;
+};
+
 export class StoreReader {
-  constructor(
-    private cacheKeyRoot = new CacheKeyNode,
-  ) {
-    const reader = this;
+  private freezeResults: boolean;
+
+  constructor({
+    cacheKeyRoot = new CacheKeyNode,
+    freezeResults = false,
+  }: StoreReaderConfig = {}) {
     const {
       executeStoreQuery,
       executeSelectionSet,
-    } = reader;
+    } = this;
+
+    this.freezeResults = freezeResults;
 
     this.executeStoreQuery = wrap((options: ExecStoreQueryOptions) => {
       return executeStoreQuery.call(this, options);
@@ -117,7 +127,7 @@ export class StoreReader {
         // underlying store is capable of tracking dependencies and invalidating
         // the cache when relevant data have changed.
         if (contextValue.store instanceof DepTrackingCache) {
-          return reader.cacheKeyRoot.lookup(
+          return cacheKeyRoot.lookup(
             query,
             contextValue.store,
             fragmentMatcher,
@@ -138,7 +148,7 @@ export class StoreReader {
         execContext,
       }: ExecSelectionSetOptions) {
         if (execContext.contextValue.store instanceof DepTrackingCache) {
-          return reader.cacheKeyRoot.lookup(
+          return cacheKeyRoot.lookup(
             selectionSet,
             execContext.contextValue.store,
             execContext.fragmentMatcher,
@@ -376,6 +386,10 @@ export class StoreReader {
     // defensive shallow copies than necessary.
     finalResult.result = mergeDeepArray(objectsToMerge);
 
+    if (this.freezeResults && process.env.NODE_ENV !== 'production') {
+      Object.freeze(finalResult.result);
+    }
+
     return finalResult;
   }
 
@@ -417,6 +431,9 @@ export class StoreReader {
     // Handle all scalar types here
     if (!field.selectionSet) {
       assertSelectionSetForIdValue(field, readStoreResult.result);
+      if (this.freezeResults && process.env.NODE_ENV !== 'production') {
+        maybeDeepFreeze(readStoreResult);
+      }
       return readStoreResult;
     }
 
@@ -495,6 +512,10 @@ export class StoreReader {
       return item;
     });
 
+    if (this.freezeResults && process.env.NODE_ENV !== 'production') {
+      Object.freeze(result);
+    }
+
     return { result, missing };
   }
 }