diff --git a/README.md b/README.md
index 1cd6f07..e888804 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,9 @@ arguments so we don't have to care about escaping spaces. It can also return
 stdout/stderr even when the command fails, or times out. Importantly, it's also
 not susceptible to max buffer issues.
 
+Published as both ESM and CommonJS, so `import {exec} from 'teen_process'` and
+`const {exec} = require('teen_process')` both work.
+
 ## teen_process.exec
 
 Examples:
diff --git a/lib/exec.ts b/lib/exec.ts
index dac2608..717df69 100644
--- a/lib/exec.ts
+++ b/lib/exec.ts
@@ -1,14 +1,14 @@
 import {spawn} from 'node:child_process';
 import {quote} from 'shell-quote';
-import {formatEnoent} from './helpers';
-import {CircularBuffer, MAX_BUFFER_SIZE} from './circular-buffer';
+import {formatEnoent} from './helpers.js';
+import {CircularBuffer, MAX_BUFFER_SIZE} from './circular-buffer.js';
 import type {
   TeenProcessExecOptions,
   TeenProcessExecResult,
   BufferProp,
   ExecError,
   StreamName,
-} from './types';
+} from './types.js';
 
 /**
  * Spawns a child process and collects its output.
diff --git a/lib/index.ts b/lib/index.ts
index 6b747d0..02a492c 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -1,9 +1,9 @@
 export {spawn} from 'node:child_process';
-export {SubProcess} from './subprocess';
-export {exec} from './exec';
+export {SubProcess} from './subprocess.js';
+export {exec} from './exec.js';
 export type {
   TeenProcessExecOptions,
   TeenProcessExecResult,
   ExecError,
   SubProcessOptions,
-} from './types';
+} from './types.js';
diff --git a/lib/subprocess.ts b/lib/subprocess.ts
index a633053..f56b900 100644
--- a/lib/subprocess.ts
+++ b/lib/subprocess.ts
@@ -2,10 +2,10 @@ import {spawn} from 'node:child_process';
 import type {ChildProcess} from 'node:child_process';
 import {EventEmitter} from 'node:events';
 import {quote} from 'shell-quote';
-import {formatEnoent} from './helpers';
+import {formatEnoent} from './helpers.js';
 import {createInterface} from 'node:readline';
 import type {Readable} from 'node:stream';
-import type {SubProcessOptions, StartDetector, TIsBufferOpts, StreamName} from './types';
+import type {SubProcessOptions, StartDetector, TIsBufferOpts, StreamName} from './types.js';
 
 /**
  * A wrapper around Node's spawn that provides event-driven process management.
diff --git a/package.json b/package.json
index 96bedb7..8fba9f8 100644
--- a/package.json
+++ b/package.json
@@ -20,20 +20,39 @@
   },
   "license": "Apache-2.0",
   "author": "Appium Contributors",
-  "main": "build/lib/index.js",
-  "types": "build/lib/index.d.ts",
+  "type": "module",
+  "main": "./build/cjs/lib/index.js",
+  "module": "./build/esm/lib/index.js",
+  "types": "./build/cjs/lib/index.d.ts",
+  "exports": {
+    ".": {
+      "import": {
+        "types": "./build/esm/lib/index.d.ts",
+        "default": "./build/esm/lib/index.js"
+      },
+      "require": {
+        "types": "./build/cjs/lib/index.d.ts",
+        "default": "./build/cjs/lib/index.js"
+      }
+    },
+    "./package.json": "./package.json"
+  },
   "bin": {},
   "directories": {
     "lib": "lib"
   },
   "files": [
     "lib",
-    "build/lib",
+    "build/cjs/lib",
+    "build/cjs/package.json",
+    "build/esm/lib",
+    "build/esm/package.json",
     "CHANGELOG.md"
   ],
   "scripts": {
-    "build": "tsc -b",
-    "clean": "npm run build -- --clean",
+    "build": "tsc -b tsconfig.esm.json tsconfig.cjs.json",
+    "postbuild": "node scripts/postbuild.mjs",
+    "clean": "node -e \"require('node:fs').rmSync('build', {recursive: true, force: true})\"",
     "dev": "npm run build -- --watch",
     "lint": "eslint .",
     "lint:fix": "npm run lint -- --fix",
@@ -42,7 +61,7 @@
     "format:check": "prettier --check ./lib ./test",
     "prepare": "npm run rebuild",
     "rebuild": "npm run clean && npm run build",
-    "test": "node --test \"./build/test/**/*.spec.js\""
+    "test": "node --test --enable-source-maps --test-timeout=60000 \"./build/esm/test/**/*.spec.js\" \"./test/*.spec.cjs\""
   },
   "prettier": {
     "bracketSpacing": false,
diff --git a/scripts/postbuild.mjs b/scripts/postbuild.mjs
new file mode 100644
index 0000000..1b0f9cf
--- /dev/null
+++ b/scripts/postbuild.mjs
@@ -0,0 +1,9 @@
+import {mkdirSync, writeFileSync} from 'node:fs';
+
+for (const [dir, type] of [
+  ['build/esm', 'module'],
+  ['build/cjs', 'commonjs'],
+]) {
+  mkdirSync(dir, {recursive: true});
+  writeFileSync(`${dir}/package.json`, `${JSON.stringify({type}, null, 2)}\n`);
+}
diff --git a/test/circular-buffer.spec.ts b/test/circular-buffer.spec.ts
index 4e60e48..91c5bdb 100644
--- a/test/circular-buffer.spec.ts
+++ b/test/circular-buffer.spec.ts
@@ -1,5 +1,5 @@
 import assert from 'node:assert/strict';
-import {CircularBuffer} from '../lib/circular-buffer';
+import {CircularBuffer} from '../lib/circular-buffer.js';
 import {describe, it} from 'node:test';
 
 describe('CircularBuffer', function () {
diff --git a/test/cjs-interop.spec.cjs b/test/cjs-interop.spec.cjs
new file mode 100644
index 0000000..2ada475
--- /dev/null
+++ b/test/cjs-interop.spec.cjs
@@ -0,0 +1,12 @@
+const assert = require('node:assert/strict');
+const {test} = require('node:test');
+// Requires the package by name (rather than a build path) so this exercises the same
+// "exports"/"main" resolution real CommonJS consumers go through.
+const teenProcess = require('teen_process');
+
+test('require() interop with the CJS build', async () => {
+  assert.equal(typeof teenProcess.exec, 'function');
+  assert.equal(typeof teenProcess.SubProcess, 'function');
+  const {code} = await teenProcess.exec('true');
+  assert.equal(code, 0);
+});
diff --git a/test/exec.spec.ts b/test/exec.spec.ts
index d77d74d..18dff59 100644
--- a/test/exec.spec.ts
+++ b/test/exec.spec.ts
@@ -1,9 +1,12 @@
 import assert from 'node:assert/strict';
 import path from 'node:path';
-import {exec} from '../lib';
-import {getFixture} from './helpers';
+import {fileURLToPath} from 'node:url';
+import {exec} from '../lib/index.js';
+import {getFixture} from './helpers.js';
 import {describe, it, type TestContext} from 'node:test';
 
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
 describe('exec', function () {
   it('should work with arguments like spawn', async function () {
     const cmd = 'ls';
diff --git a/test/helpers.ts b/test/helpers.ts
index ceafb22..61d7a35 100644
--- a/test/helpers.ts
+++ b/test/helpers.ts
@@ -1,5 +1,6 @@
 import path from 'node:path';
 import fs from 'node:fs/promises';
+import {fileURLToPath} from 'node:url';
 
 let moduleRoot: string | null = null;
 
@@ -16,7 +17,7 @@ export async function getFixture(fix: string): Promise<string> {
 }
 
 async function getModuleRoot(): Promise<string> {
-  let currentDir = path.dirname(path.resolve(__filename));
+  let currentDir = path.dirname(fileURLToPath(import.meta.url));
   let isAtFsRoot = false;
   while (!isAtFsRoot) {
     const manifestPath = path.join(currentDir, 'package.json');
diff --git a/test/subproc.spec.ts b/test/subproc.spec.ts
index 1fc1185..42bb540 100644
--- a/test/subproc.spec.ts
+++ b/test/subproc.spec.ts
@@ -1,9 +1,13 @@
 import assert from 'node:assert/strict';
 import path from 'node:path';
-import {exec, SubProcess} from '../lib';
-import {getFixture} from './helpers';
+import {fileURLToPath} from 'node:url';
+import {exec, SubProcess} from '../lib/index.js';
+import {getFixture} from './helpers.js';
 import {describe, it, beforeEach, afterEach} from 'node:test';
 
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 // Windows doesn't understand SIGHUP
 const stopSignal = process.platform === 'win32' ? 'SIGTERM' : 'SIGHUP';
 
diff --git a/tsconfig.cjs.json b/tsconfig.cjs.json
new file mode 100644
index 0000000..4dfcb4d
--- /dev/null
+++ b/tsconfig.cjs.json
@@ -0,0 +1,10 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "build/cjs",
+    "module": "CommonJS",
+    "moduleResolution": "Bundler"
+  },
+  "include": ["lib"]
+}
diff --git a/tsconfig.esm.json b/tsconfig.esm.json
new file mode 100644
index 0000000..30361d7
--- /dev/null
+++ b/tsconfig.esm.json
@@ -0,0 +1,7 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "build/esm"
+  }
+}
diff --git a/tsconfig.json b/tsconfig.json
index 7888b90..08a74be 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -9,5 +9,6 @@
   "include": [
     "lib",
     "test"
-  ]
+  ],
+  "exclude": ["test/*.cjs"]
 }