Type classes are an immensely popular and productive feature of Haskell. They have since been adopted in, and adapted to, numerous other languages, including theorem provers. This talk will show that type classes have a natural and efficient representation in .NET. This paves the way for the extension of F# and other .NET languages with Haskell style type classes. The representation is type preserving and promises easy and safe cross-language inter-operation. We are currently, and rapidly, extending the open source C# compiler and language service, Roslyn, with support for type classes but intend to do the same for F# once that work has been completed.