You need some precise combinaison of Windows and Visual Studio to target a given version of Windows Phone. At least if you want to use emulators, you'll need a

You need some precise combinaison of Windows and Visual Studio to target a given version of Windows Phone. At least if you want to use emulators, you'll need a Windows 8 to target WP8 (otherwise Win7 is fine IIRC). Windows 10 is required to build Win10M apps targeting UWP. You can still use WP8 tools (thus Win8) to make WinPRT or Silverlight apps. That's the theory. In practice the last insider build have a bug which forbid app deployment, and for some builds nows the Silverlight app runtime had its own bugs (keyboard related for example). For having used this tools since WP7 I really feel a decline in quality on the mobile OS and I wouldn't recommand to bother anymore.