Can you build Win 8 apps on Windows 7 with VS 2012?

Getting started with Windows Store apps:

"Windows Store app development is supported only on Windows 8. You can't develop Windows Store apps on Windows 7 or Windows Server 2012."

So no, it will not work on Windows 7.

You cannot develop Windows Store Apps on Windows 7 you need Windows 8 and Visual Studio 2012. There is a free version of Visual Studio Called Visual Studio Express 2012 for Windows 8. It lets you make Windows Store Apps. If you Install Visual Studio on Windows 7 it blocks the development of Windows Store Apps. So what I am trying to tell you is you need Windows 8 or Windows Server 2012 to Develop Windows Store Apps.

You can download Visual Studio Express 2012 for Windows 8 for free:

http://microsoft.com/express

You can also get a Windows 8 Trial for 90 days for free:

http://msdn.microsoft.com/en-us/evalcenter/jj554510.aspx