I am trying to set up an existing Eclipse project in IDEA 10.0.3, and am having some problems getting the compiler to recognize some precompiled .class files in the project. In eclipse this is handled by using the "Add External Class Folder" option under the Java build path libraries properties and pointing to the folder containing the .class files. In IDEA, I have tried "Attach Classes" in the Libraries section of the Project Settings, as well as adding the folder as a dependency from the Modules page. Both methods seem to make the project recognize the files, as in the Project pane their icons change to Interface, Class, etc appropriately (and "(library home)" shows up next to the folder name), but where imported in the source they are still marked as unresolved. The folder structure is unchanged from what works in Eclipse, and mirror the package name. Can anybody point me in the right direction?