Setting up a development environment for Mobile Firefox is relatively easy.
For Firefox for Android, just follow our [https://developer.mozilla.org/en-US/docs/Simple_Firefox_for_Android_build|build instructions]] and you'll be ready to start hacking after a couple of hours—mostly waiting for everything to compile. Unfortunately, Firefox for Android is more complicated than a basic Android app, so we recommend that you're comfortable using a command line before getting started.
While you're waiting for your build, take a look at our [[Mobile/Fennec/Android/Suggested workflow|suggested workflow]] page.