Can I compile .NET C# code on my Mac?

I need a way to cross compile a short piece of .NET C# code to a dll, which will then run a client's Windows environment. I run OS X 10.9.2 on an iMac. Does anyone know what tools allow this? I would rather not install Parallels and Windows if I can find a way to cross compile this without needing that heavy of an installation of Microsoft tools.