Hi, I tried to compile boost python so that it links against the debug version. I therefore run bjam toolset=msvc-9.0 threading=multi python-debugging=on link=shared variant=debug libs\python\build Running it with -n shows, that it sets -DBOOST_DEBUG_PYTHON, but it still links with python25.lib. It only picks "right" python25_d.lib, if I add something to my user-config.jam, like the following: using python : 2.5 : C:\\src\\Python-2.5\\PCBuild\\python ; using python : 2.5 : C:\\src\\Python-2.5\\PCBuild\\python_d : # includes : # libs : <python-debugging>on ; What is the difference between the two methods (as a bjam argument and in the user-config.jam), and is there a way to combine both on the command line? Thanks and regards, Chris