Q:

Why is MonoDevelop compiling with csc.exe? 

I am trying to use MonoDevelop (2.4 beta 1) on Windows (7 x64) in order to test a .NET application on Mono (2.6.4).  For some reason MonoDevelop is not using the Mono tool chain to build the application.  It compiles it with the Microsoft tool chain - C:\Windows\Microsoft. NET\Framework\v3.5\csc.exe.  The project I am trying to build is a simple ASP.NET MVC application generated from the "New ASP.NET MVC application" template. 
The "Runtime Version" dropdown in Project \Options->Build->General shows "MONO/.NET 35".  What gives?  Is there a way to change the .NET tool chain? 

A:

First of all, make sure that you have Mono installed.  MonoDevelop does not include the Mono runtime, so you'll have to install it separately. 
Once you have the Mono runtime installed, there are several ways of choosing the .NET toolchain to be used for building and running applications. 
If you plan to build and run mostly on Mono, you can set the Mono runtime as default runtime for MonoDevelop.  To do it, go to Edit->Preferences->.NET Runtimes, select the Mono runtime and click on "Select as Default". 
If you plan to work on Mono only for some projects, you can temporarily switch the target runtime using the Project->Active Runtime menu, or by selecting it in the configuration combobox in the toolbar.