can I use .net 3.5 binaries for a library with a .net 4.0 application / what are the negatives if any?

Can I use .net 3.5 binaries for a library with a .net 4.0 application / what are the negatives if any? In other words is there any reason I should take more time out to download source for the library and build it under .net 4.0 (assuming it builds without any problems I guess) as opposed to downloading the .net 3.5 binaries.

I'm using C#开发者_如何学运维 in VS2010.

thanks

.NET 4.0 is compatible with .NET 3.5 and earlier, but as comments below indicate, best practice would be to recompile with .NET 4.0 when you can.

It is safe (and intended) that you can use assemblies targeting older versions of the framework.

No problems whatsoever. No expected ones anyway but I bet ya microsoft has one up their sleve, they tend to work in mysterious ways :)

It should be fine but there are some issues that can arise but might now be fixed in the release version. See:

http://krishnabhargav.blogspot.com/2010/02/using-net-35-clr-20-dll-inside-visual.html

Read Microsoft's advice about .NET 4.0 compatibility in this article: Version Compatibility in the .NET Framework.