Ownership can be a tricky question, but usually SWIG is pretty explicit about which memory/objects it owns and which it doesn't. Like the other poster I also often thought that my program was leaking memory as the Python interpreter does not immediately release unused memory, so even if everything is fine it can seem like your program is consuming more and more memory (explicitly collecting garbage using `gc.collect()` usually helps here). In general, you should be really clear about who owns a given object (either the C/C++-side of your code or the Python side) and avoid passing ownership back and forth between the two. I already mapped some pretty intricate code using SWIG (including a parser generator that created lots of object instances in C++ and passed them to Lua for manipulation, and where the Lua side could also create objects and link them to the C++-created objects) and so far didn't have any problems with memory leaks due to the binding code.