Compile dll as earlier build

When I try to run the dll I compiled in Visual Studio 2010, I get the following message: This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded. I'm gues开发者_如何学JAVAsing this means that I am a too recent version of Visual Studio. Is there a way I can build the dll as an earlier version?

All assemblies in your final solution, be they dlls or exes, in different solutions or in the same one, must target the same version of the CLR. You can ensure they do by configuring targeting in your 2010 solution.

Most likely you're targeting 4.0 in your dll's project. Crank it back to 3.5 or earlier and see if that fixes the problem.