"C# has been a language with a mixed history but precise goals. Although the C# language definition is for some time an ISO standard, only a part of the Base Class Library, which contains the fundamental functions that are used by all C# programs (IO, User Interface, Web services, etc) is also standardized. Parts of the BCL have been patented by Microsoft, but that has not deterred developers from attempts at implementing the components that are standardized, in various forms (Mono and affiliated projects). What happens when you go beyond that? What happens when outside the language, you start to implement not a mere application platform, but an entire operating system around it? Brace yourselves, because there is not only Microsoft Research who has done this with Singularity, but at least two other projects doing the same; and they are doing this under opensource terms. A system based around a C# Kernel. In this article, we are looking at one of the two, Cosmos by asking Scott Balmos and Chad Hower about the project they are involved in."