title: Can an x64 application use x86 assemblies - and vice versa?
body: <p>My application is built as a x64 application. After moving to VS2010 I got <a href="https://stackoverflow.com/questions/2688993/problem-with-sqlite-related-nunit-tests-after-upgrade-to-vs2010-and-re5">some problems</a> which seems to be related to some x64/x86 mismatch in referenced dlls. Now I'm moving to target .NET4, and I get even more <a href="https://stackoverflow.com/questions/2697795/using-fluentnhibernate-with-net4">similar problems</a>. </p>
  
  <p>My question is: What precautions do I need to take regarding mixing x64 and x86. Can it be done at all? I thought x64 applications should be able to use x86 dlls without problems. No? What about the other way? Can a x86 application reference an x64 dll - as long as it is being run on an x64 platform? What are the pitfalls I need to be aware of? </p>