diff --git a/packages/ram-composition-root/package.json b/packages/ram-composition-root/package.json
index 83b115b..125665a 100644
--- a/packages/ram-composition-root/package.json
+++ b/packages/ram-composition-root/package.json
@@ -18,6 +18,7 @@
     "build": "cpr ./src ./dist -d"
   },
   "dependencies": {
+    "chokidar": "^3.4.2",
     "dot-object": "^1.7.1",
     "lodash": "^4.17.15",
     "minimist": "^1.2.5"
diff --git a/packages/ram-composition-root/src/bin/build-usage.txt b/packages/ram-composition-root/src/bin/build-usage.txt
new file mode 100644
index 0000000..b0b3377
--- /dev/null
+++ b/packages/ram-composition-root/src/bin/build-usage.txt
@@ -0,0 +1,9 @@
+Usage: composition-root build <search-root> <rule> [options]
+
+  Generates composition root files in a <search-root> folder for a <rule> from composition configuration file.
+
+Options:
+
+  -c <file>, --config <file>      composition config file (default: "composition-config.json").
+  -o <file>, --output <file>     output file
+  -h, --help                      Display this usage info.
diff --git a/packages/ram-composition-root/src/bin/build.js b/packages/ram-composition-root/src/bin/build.js
new file mode 100644
index 0000000..eec5c77
--- /dev/null
+++ b/packages/ram-composition-root/src/bin/build.js
@@ -0,0 +1,39 @@
+const fs = require('fs');
+const path = require('path');
+
+const {loadConfig} = require('../config-loader');
+const {resolveContext} = require('../resolver');
+
+module.exports = {build};
+
+function build(searchRoot, referencedRule, configFile = 'composition-config.json', outputFile) {
+  const searchPath = path.resolve(process.cwd(), searchRoot);
+  const configAbsolutePath = path.resolve(searchPath, configFile);
+
+  console.log('Loading config', require.resolve(configAbsolutePath));
+  const compositionConfig = loadConfig(configAbsolutePath);
+
+  const {plugins, rules, compositionRoots} = compositionConfig;
+
+  const context = {
+    referencedRule,
+    cwd: searchPath,
+    basePath: path.relative(process.cwd(), searchRoot),
+    configAbsolutePath,
+    rootPath: '.',
+    plugins,
+    rules,
+    compositionRoots,
+  };
+
+  const output = resolveContext(context);
+
+  if (!output) {
+    console.warn(`No files matched "${referencedRule}" rule in ${searchPath}`);
+  }
+
+  if (outputFile) {
+    fs.writeFileSync(path.resolve(searchPath, outputFile), output);
+  }
+}
+
diff --git a/packages/ram-composition-root/src/bin/cli-usage.txt b/packages/ram-composition-root/src/bin/cli-usage.txt
new file mode 100644
index 0000000..ba865aa
--- /dev/null
+++ b/packages/ram-composition-root/src/bin/cli-usage.txt
@@ -0,0 +1,11 @@
+Usage: composition-root <command> [options]
+
+Commands:
+
+  build                           Build composition root
+  watch                           Watch for new files
+
+Options:
+
+  -h, --help                      Display this usage info.
+  -v, --version                   Display the composition-root version.
diff --git a/packages/ram-composition-root/src/bin/cli.js b/packages/ram-composition-root/src/bin/cli.js
index a37c367..31d8f5f 100644
--- a/packages/ram-composition-root/src/bin/cli.js
+++ b/packages/ram-composition-root/src/bin/cli.js
@@ -1,10 +1,8 @@
-const _ = require('lodash/fp');
 const fs = require('fs');
-const path = require('path');
 const minimist = require('minimist');
 
-const {loadConfig} = require('../config-loader');
-const {resolveContext} = require('../resolver');
+const {build} = require('./build');
+const {watch} = require('./watch');
 
 const argv = minimist(process.argv.slice(2), {
   alias: {
@@ -20,42 +18,28 @@ if (argv.v) {
   return;
 }
 
-if (argv.h || !argv._[0]) {
-  fs.createReadStream(__dirname + '/usage.txt').pipe(process.stdout);
-  return;
-}
-
-const searchRoot = argv._[1];
-const referencedRule = argv._[2];
-
-const searchPath = path.resolve(process.cwd(), searchRoot);
-const configFile = argv.c || 'composition-config.json';
-const configAbsolutePath = path.resolve(searchPath, configFile);
-
-console.log('Loading config', require.resolve(configAbsolutePath));
-const compositionConfig = loadConfig(configAbsolutePath);
-
-
-const {plugins, rules, compositionRoots} = compositionConfig;
-
-const context = {
-  referencedRule,
-  cwd: searchPath,
-  basePath:  path.relative(process.cwd(), searchRoot),
-  configAbsolutePath,
-  rootPath: '.',
-  plugins,
-  rules,
-  compositionRoots,
-}
-
-const output = resolveContext(context);
-
-if (!output) {
-  console.warn(`No files matched "${referencedRule}" rule in ${searchPath}`);
+if (argv.h) {
+  switch (argv._[0]) {
+    case 'build':
+      fs.createReadStream(__dirname + '/build-usage.txt').pipe(process.stdout);
+      return;
+    case 'watch':
+      fs.createReadStream(__dirname + '/watch-usage.txt').pipe(process.stdout);
+      return;
+    default:
+      fs.createReadStream(__dirname + '/cli-usage.txt').pipe(process.stdout);
+      return;
+  }
 }
 
-let outputFile = argv.o;
-if (outputFile) {
-  fs.writeFileSync(path.resolve(searchPath, outputFile), output);
+switch (argv._[0]) {
+  case 'build':
+    build(argv._[1], argv._[2], argv.c, argv.o);
+    return;
+  case 'watch':
+    watch(argv._[1], argv._[2]);
+    return;
+  default:
+    fs.createReadStream(__dirname + '/cli-usage.txt').pipe(process.stdout);
+    return;
 }
diff --git a/packages/ram-composition-root/src/bin/usage.txt b/packages/ram-composition-root/src/bin/usage.txt
deleted file mode 100644
index 93a8e31..0000000
--- a/packages/ram-composition-root/src/bin/usage.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-Usage: composition-root build <rule> <search-root> [options]
-
-  Generates composition root files in a "search-root" folder for a "rule" from composition configuration file.
-
-Options:
-
-  -c <file>, --config <file>      composition config file (default: "composition-config.json").
-  -o <file>, --output <file>     output file
-  -h, --help                      Display this usage info.
-  -v, --version                   Display the cpr version.
-
diff --git a/packages/ram-composition-root/src/bin/watch-usage.txt b/packages/ram-composition-root/src/bin/watch-usage.txt
new file mode 100644
index 0000000..b2eb19d
--- /dev/null
+++ b/packages/ram-composition-root/src/bin/watch-usage.txt
@@ -0,0 +1,5 @@
+Usage: composition-root watch <search-root> <file> [options]
+
+  Watches <search-root> and updates target <file> timestamps whenever source files are added or deleted. This forces Babel to rerun macros within target <file>.
+
+  -h, --help                      Display this usage info.
diff --git a/packages/ram-composition-root/src/bin/watch.js b/packages/ram-composition-root/src/bin/watch.js
new file mode 100644
index 0000000..8af2860
--- /dev/null
+++ b/packages/ram-composition-root/src/bin/watch.js
@@ -0,0 +1,38 @@
+const fs = require('fs');
+const path = require('path');
+const chokidar = require('chokidar');
+
+module.exports = {watch};
+
+function watch(cwd, filename) {
+  const fileToUpdate =  path.join(cwd, filename);
+
+  console.log(`Watching ${cwd} for new files.`);
+
+  const watcher = chokidar.watch([
+    path.join(cwd, '**/*.tsx'),
+    path.join(cwd, '**/*.ts'),
+    path.join(cwd, '**/*.js'),
+    path.join(cwd, '**/*.jsx'),
+  ], {
+    ignored: fileToUpdate,
+    persistent: true,
+  });
+
+  watcher.on('ready', () => {
+    watcher
+      .on('add', path => {
+        console.log(`File ${path} has been added`);
+        return invalidateCache(fileToUpdate);
+      })
+      .on('unlink', path => {
+        console.log(`File ${path} has been removed`);
+        return invalidateCache(fileToUpdate);
+      });
+  });
+}
+
+function invalidateCache(fileName) {
+  console.log(`Updating ${fileName}`)
+  fs.utimesSync(fileName, new Date(), new Date());
+}
diff --git a/packages/ram-sample-app/package.json b/packages/ram-sample-app/package.json
index 0a689a3..08b88c6 100644
--- a/packages/ram-sample-app/package.json
+++ b/packages/ram-sample-app/package.json
@@ -10,7 +10,9 @@
   "scripts": {
     "generate-composition": "composition-root build ./src Module",
     "prestart": "npm run generate-composition",
-    "start": "react-scripts start",
+    "watch": "composition-root watch ./src index.tsx",
+    "serve": "react-scripts start",
+    "start": "npm-run-all -p watch serve",
     "prebuild": "npm run generate-composition",
     "build": "react-scripts build",
     "test": "react-scripts test --env=jsdom",
@@ -22,6 +24,7 @@
     "@types/jest": "^25.2.3",
     "@types/lodash": "^4.14.152",
     "@types/node": "^14.0.5",
+    "npm-run-all": "^4.1.5",
     "patch-package": "^6.2.2",
     "postinstall-postinstall": "^2.1.0",
     "react-scripts": "^3.4.1",
diff --git a/yarn.lock b/yarn.lock
index abd06f5..7a5b04b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3804,6 +3804,21 @@ chokidar@^3.3.0, chokidar@^3.4.0:
   optionalDependencies:
     fsevents "~2.1.2"
 
+chokidar@^3.4.2:
+  version "3.4.2"
+  resolved "https://registry.yarnpkg.com/chokidar/-/chokidar-3.4.2.tgz#38dc8e658dec3809741eb3ef7bb0a47fe424232d"
+  integrity sha512-IZHaDeBeI+sZJRX7lGcXsdzgvZqKv6sECqsbErJA4mHWfpRrD8B97kSFN4cQz6nGBGiuFia1MKR4d6c1o8Cv7A==
+  dependencies:
+    anymatch "~3.1.1"
+    braces "~3.0.2"
+    glob-parent "~5.1.0"
+    is-binary-path "~2.1.0"
+    is-glob "~4.0.1"
+    normalize-path "~3.0.0"
+    readdirp "~3.4.0"
+  optionalDependencies:
+    fsevents "~2.1.2"
+
 chownr@^1.1.1, chownr@^1.1.2:
   version "1.1.4"
   resolved "https://registry.yarnpkg.com/chownr/-/chownr-1.1.4.tgz#6fc9d7b42d32a583596337666e7d08084da2cc6b"
@@ -8340,6 +8355,11 @@ memory-fs@^0.5.0:
     errno "^0.1.3"
     readable-stream "^2.0.1"
 
+memorystream@^0.3.1:
+  version "0.3.1"
+  resolved "https://registry.yarnpkg.com/memorystream/-/memorystream-0.3.1.tgz#86d7090b30ce455d63fbae12dda51a47ddcaf9b2"
+  integrity sha1-htcJCzDORV1j+64S3aUaR93K+bI=
+
 meow@^3.3.0:
   version "3.7.0"
   resolved "https://registry.yarnpkg.com/meow/-/meow-3.7.0.tgz#72cb668b425228290abbfa856892587308a801fb"
@@ -8980,6 +9000,21 @@ npm-pick-manifest@^3.0.0:
     npm-package-arg "^6.0.0"
     semver "^5.4.1"
 
+npm-run-all@^4.1.5:
+  version "4.1.5"
+  resolved "https://registry.yarnpkg.com/npm-run-all/-/npm-run-all-4.1.5.tgz#04476202a15ee0e2e214080861bff12a51d98fba"
+  integrity sha512-Oo82gJDAVcaMdi3nuoKFavkIHBRVqQ1qvMb+9LHk/cF4P6B2m8aP04hGf7oL6wZ9BuGwX1onlLhpuoofSyoQDQ==
+  dependencies:
+    ansi-styles "^3.2.1"
+    chalk "^2.4.1"
+    cross-spawn "^6.0.5"
+    memorystream "^0.3.1"
+    minimatch "^3.0.4"
+    pidtree "^0.3.0"
+    read-pkg "^3.0.0"
+    shell-quote "^1.6.1"
+    string.prototype.padend "^3.0.0"
+
 npm-run-path@^2.0.0:
   version "2.0.2"
   resolved "https://registry.yarnpkg.com/npm-run-path/-/npm-run-path-2.0.2.tgz#35a9232dfa35d7067b4cb2ddf2357b1871536c5f"
@@ -9617,6 +9652,11 @@ picomatch@^2.0.4, picomatch@^2.2.1:
   resolved "https://registry.yarnpkg.com/picomatch/-/picomatch-2.2.2.tgz#21f333e9b6b8eaff02468f5146ea406d345f4dad"
   integrity sha512-q0M/9eZHzmr0AulXyPwNfZjtwZ/RBZlbN3K3CErVrk50T2ASYI7Bye0EvekFY3IP1Nt2DHu0re+V2ZHIpMkuWg==
 
+pidtree@^0.3.0:
+  version "0.3.1"
+  resolved "https://registry.yarnpkg.com/pidtree/-/pidtree-0.3.1.tgz#ef09ac2cc0533df1f3250ccf2c4d366b0d12114a"
+  integrity sha512-qQbW94hLHEqCg7nhby4yRC7G2+jYHY4Rguc2bjw7Uug4GIJuu1tvf2uHaZv5Q8zdt+WKJ6qK1FOI6amaWUo5FA==
+
 pify@^2.0.0, pify@^2.3.0:
   version "2.3.0"
   resolved "https://registry.yarnpkg.com/pify/-/pify-2.3.0.tgz#ed141a6ac043a849ea588498e7dca8b15330e90c"
@@ -11618,7 +11658,7 @@ shebang-regex@^3.0.0:
   resolved "https://registry.yarnpkg.com/shebang-regex/-/shebang-regex-3.0.0.tgz#ae16f1644d873ecad843b0307b143362d4c42172"
   integrity sha512-7++dFhtcx3353uBaq8DDR4NuxBetBzC7ZQOhmTQInHEd6bSrXdiEyzCvG07Z44UYdLShWUyXt5M/yhz8ekcb1A==
 
-shell-quote@1.7.2:
+shell-quote@1.7.2, shell-quote@^1.6.1:
   version "1.7.2"
   resolved "https://registry.yarnpkg.com/shell-quote/-/shell-quote-1.7.2.tgz#67a7d02c76c9da24f99d20808fcaded0e0e04be2"
   integrity sha512-mRz/m/JVscCrkMyPqHc/bczi3OQHkLTqXHEFu0zDhK/qfv3UcOA4SVmRCLmos4bhjr9ekVQubj/R7waKapmiQg==
@@ -12045,6 +12085,14 @@ string.prototype.matchall@^4.0.2:
     regexp.prototype.flags "^1.3.0"
     side-channel "^1.0.2"
 
+string.prototype.padend@^3.0.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/string.prototype.padend/-/string.prototype.padend-3.1.0.tgz#dc08f57a8010dc5c153550318f67e13adbb72ac3"
+  integrity sha512-3aIv8Ffdp8EZj8iLwREGpQaUZiPyrWrpzMBHvkiSW/bK/EGve9np07Vwy7IJ5waydpGXzQZu/F8Oze2/IWkBaA==
+  dependencies:
+    define-properties "^1.1.3"
+    es-abstract "^1.17.0-next.1"
+
 string.prototype.trimend@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/string.prototype.trimend/-/string.prototype.trimend-1.0.1.tgz#85812a6b847ac002270f5808146064c995fb6913"