.NET framework versions?

Question

If you develop in .NET framework 1.1 do you have to include 1.0 as well? Also if I install .NET framework 2.0 or any future frameworks can do I have to include the previous frameworks in my distribution or do these frameworks act as a completely new version? Example: Develop app on the .NET framework 1.1 then install framework 2.0, can I just recompile the app and only include framework 2.0 in the distribution? Thanks