.NET 3.5 runtime and .NET 4 runtime compatibility

Question

Is it possible to run an application built on .NET 3.5 with a plug-in built with .NET 4?

Answer 1

Yes/No. To run the 4.0 component you must be running in the context of the .NET 4.0 runtime. However, your 3.5 application can run in the 4.0 runtime.