Couple of things. Currently there is no way to pass custom options through setuptools "develop" to distutils build_ext. What this means in practice is that you cannot do the following things: • pass the --debug flag to build_ext so as to have your module build against debug libraries. • pass any of the SWIG options through. • I'm sure there are other limitations. Because of this I ended up abandoning the swig functionality of distutils and running that as a pre distuils phase of my build scripts - it would be better If I could use it through distutils though. The show stopper is the fact I can't build against debug libraries - this means I cannot mix the --debug type builds and the develop functionality, something that seems like a logical thing to do. Is there any chance that someone could find a way to allow options to be passed through to build_ext as it is run? I'm sure its just a case of adding another option to setuptools develop and then passing it through at the relevant point. If noone wants to take it on I'm happy to write a patch if we all agree its the way to go. Thanks in advance Jamie