Microsoft has released .NET, a platform dependent standard for the C#,programming language. Sponsored by Ximian/Novell, Mono, the open source development platform based on the .NET framework, has been developed to be a platform independent version of the C#,programming environment. While .NET is platform dependent, Mono allows developers to build Linux and crossplatform applications. Mono’s .NET implementation is based on the ECMA standards for C#. This paper examines both of these programming environments with the goal of evaluating the performance characteristics of each. Testing is done with various algorithms. We also assess the trade-offs associated with using a cross-platform versus a platform