diff --git a/src/storage/common_storage.ts b/src/storage/common_storage.ts
index 1afe4a22..5a0cc424 100644
--- a/src/storage/common_storage.ts
+++ b/src/storage/common_storage.ts
@@ -32,6 +32,8 @@ import { createGeneratorContext } from '../editor/generator_context';
 
 // Types, constants, and functions related to modules, regardless of where the modules are stored.
 
+export const CURRENT_VERSION = '0.1';
+
 export type Module = {
   modulePath: string,
   moduleType: string,
@@ -90,11 +92,13 @@ const MARKER_BLOCKS_CONTENT = 'blocksContent: ';
 const MARKER_METHODS = 'methods: ';
 const MARKER_MODULE_TYPE = 'moduleType: ';
 const MARKER_COMPONENTS = 'components: ';
+const MARKER_VERSION = 'version: ';
 const PARTS_INDEX_BLOCKS_CONTENT = 0;
 const PARTS_INDEX_METHODS = 1;
 const PARTS_INDEX_MODULE_TYPE = 2;
 const PARTS_INDEX_COMPONENTS = 3;
-const NUMBER_OF_PARTS = 4;
+const PARTS_INDEX_VERSION = 4;
+const NUMBER_OF_PARTS = 5;
 
 export const UPLOAD_DOWNLOAD_FILE_EXTENSION = '.blocks';
 
@@ -572,12 +576,17 @@ export function makeModuleContent(
   pythonCode: string,
   blocksContent: string,
   methodsContent: string,
-  componentsContent: string): string {
+  componentsContent: string,
+  optVersionContent?: string): string {
+
+  const versionContent = optVersionContent ? optVersionContent : CURRENT_VERSION;
+
   let delimiter = DELIMITER_PREFIX;
   while (module.moduleType.includes(delimiter)
       || blocksContent.includes(delimiter)
       || methodsContent.includes(delimiter)
-      || componentsContent.includes(delimiter)) {
+      || componentsContent.includes(delimiter)
+      || versionContent.includes(delimiter)) {
     delimiter += '.';
   }
   return (
@@ -585,6 +594,8 @@ export function makeModuleContent(
     pythonCode + '\n\n\n' +
     '"""\n' +
     delimiter + '\n' +
+    MARKER_VERSION + versionContent + '\n' +
+    delimiter + '\n' +
     MARKER_COMPONENTS + componentsContent + '\n' +
     delimiter + '\n' +
     MARKER_MODULE_TYPE + module.moduleType + '\n' +
@@ -639,6 +650,10 @@ function getParts(moduleContent: string): string[] {
     // This module was saved without components.
     parts.push(MARKER_COMPONENTS + '[]');
   }
+  if (parts.length <= PARTS_INDEX_VERSION) {
+    // This module was saved without version.
+    parts.push(MARKER_VERSION + '0.0');
+  }
   return parts;
 }
 
@@ -692,6 +707,18 @@ export function extractComponents(moduleContent: string): Component[] {
   return components;
 }
 
+/**
+ * Extract the version from the given module content.
+ */
+export function extractVersion(moduleContent: string): string {
+  const parts = getParts(moduleContent);
+  let versionContent = parts[PARTS_INDEX_VERSION];
+  if (versionContent.startsWith(MARKER_VERSION)) {
+    versionContent = versionContent.substring(MARKER_VERSION.length);
+  }
+  return versionContent;
+}
+
 /**
  * Produce the blob for downloading a project.
  */
@@ -737,6 +764,10 @@ function _processModuleContentForDownload(
   if (componentsContent.startsWith(MARKER_COMPONENTS)) {
     componentsContent = componentsContent.substring(MARKER_COMPONENTS.length);
   }
+  let versionContent = parts[PARTS_INDEX_VERSION];
+  if (versionContent.startsWith(MARKER_VERSION)) {
+    versionContent = versionContent.substring(MARKER_VERSION.length);
+  }
 
   const module: Module = {
     modulePath: makeModulePath(projectName, moduleName),
@@ -750,7 +781,12 @@ function _processModuleContentForDownload(
   // Clear out the python content.
   const pythonCode = '';
   return makeModuleContent(
-    module, pythonCode, blocksContent, methodsContent, componentsContent);
+      module,
+      pythonCode,
+      blocksContent,
+      methodsContent,
+      componentsContent,
+      versionContent);
 }
 
 /**
@@ -826,6 +862,10 @@ export function _processUploadedModule(
   projectName: string, filename: string, uploadedContent: string)
   : [string, string, string] {
   const parts = getParts(uploadedContent);
+  let versionContent = parts[PARTS_INDEX_VERSION];
+  if (versionContent.startsWith(MARKER_VERSION)) {
+    versionContent = versionContent.substring(MARKER_VERSION.length);
+  }
   let blocksContent = parts[PARTS_INDEX_BLOCKS_CONTENT];
   if (blocksContent.startsWith(MARKER_BLOCKS_CONTENT)) {
     blocksContent = blocksContent.substring(MARKER_BLOCKS_CONTENT.length);
@@ -869,6 +909,11 @@ export function _processUploadedModule(
     headlessBlocklyWorkspace, generatorContext);
 
   const moduleContent = makeModuleContent(
-    module, pythonCode, blocksContent, methodsContent, componentsContent);
+      module,
+      pythonCode,
+      blocksContent,
+      methodsContent,
+      componentsContent,
+      versionContent);
   return [moduleName, moduleType, moduleContent];
 }