Hi all, The current SVN (and upcoming releases) includes changes to support a refactored, IronPython-compatible import syntax and assembly load behavior. Where in releases to date you had to use the magic 'CLR' module as the root of all CLR imports, now you can just say: from System import * The old 'CLR' syntax is deprecated but will continue to work until pythonnet 3.x. A second job of the artist-formerly-known-as-the-magic-CLR-module was to provide a way to bootstrap CLR support in an existing CPython installation (by providing a pseudo- C-extension). In other words, you had to say 'import CLR' before using .NET from an stock Python install. The next releases will continue to include an (upper-case) "CLR" extension for b/w compatibility, but it will also include a (lower-case) "clr" module that is call-compatible with the clr module from IronPython. The new "clr" module will provide the IP-compatible AddReference APIs to support explicit loading of assembly dependencies, and it will also become the officially supported way of bootstrapping CLR support in a stock Python install. So if you want to use .NET from an existing Python install or ensure that your code is portable between IP and PythonNet, you should either arrange for your app to 'import clr' before using .NET features, or to advise users to add 'import clr' to their sitecustomize.py. I've tried hard to look at this from every angle and make sure this is not a breaking change for 2.x (though it will be for 3.x), but if you're building on pythonnet and this will cause you any problems, please let me know soonest. - Brian