If I have a package installed as a zip file egg and ask for its __file__ I might get a reference which looks like a normal file system path but isn't: % python Python 2.4.5 (#4, Apr 12 2008, 09:09:16) [GCC 3.4.1] on sunos5 Type "help", "copyright", "credits" or "license" for more information. >>> import magnitude >>> magnitude.__file__ '/opt/app/g++lib6/python-2.4/lib/python2.4/site-packages/magnitude-0.9.3-py2.4.egg/magnitude.pyc' >>> magnitude.__file__[:-1] '/opt/app/g++lib6/python-2.4/lib/python2.4/site-packages/magnitude-0.9.3-py2.4.egg/magnitude.py' >>> import os >>> os.path.exists(magnitude.__file__[:-1]) False How do I actually lay my hands on the .py file source for the magnitude module in this case? Do I have to recognize somehow that .../magnitude-0.9.3-py2.4.egg is a zip archive and resort to extracting the Python source with the zipfile module? Thx, Skip Montanaro