Is it okay to install .NET 3.5 if I already have .NET 4.0 installed?

Question

I have a Windows 7 laptop which has .NET 4 installed.

It also has folders for version 2, 3 and 3.5 of the .NET framework in the %WinDir%, but the main assemblies such as mscorlib.dll etc. are only present in the folders designated for versions 2.0 and 4.0. The rest of them have a very few DLLs and mostly just config files.

My goal is to compare the members in an assembly of version 3.5 with that of version 4 of the same dll.

My questions are: a) Can I install version 3.5 from the Microsoft website and then compare the two versions?

b) If I do install version 3.5 now, will that screw up with the version 4 that is already installed on my machine?

Answer 1

Yes.

You can install and run multiple versions of the .NET Framework on a computer. You can install the versions in any order.

http://msdn.microsoft.com/en-us/library/y549e41e%28v=vs.90%29.aspx

For your first question, you could also take a look at MSDN documentations and compare those, but having .NET 3.5 might not hurt if you are planning on using it anyway.