diff --git a/README.md b/README.md
index 00d0839c8..43b5a5a79 100644
--- a/README.md
+++ b/README.md
@@ -97,7 +97,7 @@ export const sum = (a: number, b: number) => {
 };
 ```
 
-`tsdx build` will output an ES module file and 3 CommonJS files (dev, prod, and an entry file). If you want to specify a UMD build, you can do that as well. For brevity, let's examine the CommonJS output (comments added for emphasis):
+`tsdx build` will output an 3 files for CommonJS and ES formats (dev, prod, and an entry file). If you want to specify a UMD build, you can do that as well. For brevity, let's examine the CommonJS output (comments added for emphasis):
 
 ```js
 // Entry File
diff --git a/src/index.ts b/src/index.ts
index 8bfb66824..6634ea4ce 100755
--- a/src/index.ts
+++ b/src/index.ts
@@ -95,6 +95,8 @@ function createBuildConfigs(
         createRollupConfig('cjs', 'development', { ...opts, input }),
       opts.format.includes('cjs') &&
         createRollupConfig('cjs', 'production', { ...opts, input }),
+      opts.format.includes('es') &&
+        createRollupConfig('es', 'development', { ...opts, input }),
       opts.format.includes('es') &&
         createRollupConfig('es', 'production', { ...opts, input }),
       opts.format.includes('umd') &&
@@ -337,33 +339,29 @@ prog
     opts.name = opts.name || appPackageJson.name;
     opts.input = await getInputs(opts.entry, appPackageJson.source);
     const buildConfigs = createBuildConfigs(opts);
+
+    let promise = Promise.resolve();
+
+    if (opts.format.length > 0) {
+      promise.then(() => util.promisify(mkdirp)(resolveApp('./dist')));
+    }
+
     if (opts.format.includes('cjs')) {
-      try {
-        await util.promisify(mkdirp)(resolveApp('./dist'));
-        const promise = fs
-          .writeFile(
-            resolveApp('./dist/index.js'),
-            `
-         'use strict'
+      logger(
+        promise.then(() => writeEntryFile('cjs')).catch(logError),
+        'Creating CJS entry file'
+      );
+    }
 
-      if (process.env.NODE_ENV === 'production') {
-        module.exports = require('./${safePackageName(
-          opts.name
-        )}.cjs.production.js')
-      } else {
-        module.exports = require('./${safePackageName(
-          opts.name
-        )}.cjs.development.js')
-      }`
-          )
-          .catch(e => {
-            throw e;
-          });
-        logger(promise, 'Creating entry file');
-      } catch (e) {
-        logError(e);
-      }
+    if (opts.format.includes('es')) {
+      logger(
+        promise.then(() => writeEntryFile('es')).catch(logError),
+        'Creating ES entry file'
+      );
     }
+
+    await promise;
+
     try {
       const promise = asyncro
         .map(
@@ -381,6 +379,22 @@ prog
     } catch (error) {
       logError(error);
     }
+
+    function writeEntryFile(format: string) {
+      // prettier-ignore
+      const baseLine = `  module.exports = require('./${safePackageName(opts.name)}.${format}`;
+      return fs.writeFile(
+        resolveApp(`./dist/index${format !== 'cjs' ? `.${format}` : ''}.js`),
+        [
+          `'use strict'`,
+          `if (process.env.NODE_ENV === 'production') {`,
+          `${baseLine}.production.js')`,
+          '} else {',
+          `${baseLine}.development.js')`,
+          '}',
+        ].join('\n')
+      );
+    }
   });
 
 prog
diff --git a/test/tests/tsdx-build.test.js b/test/tests/tsdx-build.test.js
index 3f56da165..fc931f9bb 100644
--- a/test/tests/tsdx-build.test.js
+++ b/test/tests/tsdx-build.test.js
@@ -21,12 +21,16 @@ describe('tsdx build', () => {
     const output = shell.exec('node ../dist/index.js build');
 
     expect(shell.test('-f', 'dist/index.js')).toBeTruthy();
+    expect(shell.test('-f', 'dist/index.es.js')).toBeTruthy();
     expect(
       shell.test('-f', 'dist/build-default.cjs.development.js')
     ).toBeTruthy();
     expect(
       shell.test('-f', 'dist/build-default.cjs.production.js')
     ).toBeTruthy();
+    expect(
+      shell.test('-f', 'dist/build-default.es.development.js')
+    ).toBeTruthy();
     expect(
       shell.test('-f', 'dist/build-default.es.production.js')
     ).toBeTruthy();