Hi, Yesterday I upgraded boost to 1.4, from 1.36. A big jump, but hey why not. I'm running OSX, 10.6 with the most recent dev tools ( Xcode 3.2, GCC 4.2, etc ) and used the bjam build system as described on the website. Vanilla install to /usr/local/ giving me the static and dynamic libs in /usr/local/lib. Two (related) questions: 1) My project ( built in Xcode ) uses mostly header-based libs, but does link against libboost_thread.a -- and now it throws all sorts of linker errors when it worked just fine linking against 1.36 For example: "boost::thread::~thread()", referenced from: void boost::checked_deleteboost::thread(boost::thread*)in QTFrameTransfer.o /// many many more And for reference, I really *am* linking against libboost_thread.a 2) My related followup question -- I've *never* been able to link against libboost_python.a. So in the past I added the full source from $BOOST/libs/python/src to a sub-target of my project and manually build my own libboost_python.a which I then linked against. That worked fine. But I don't understand why I can't link against /usr/ local/lib/libboost_python.a I have to assume something's wonky with the way bjam is building these libraries. But I'm following the out-of-the-box install instructions. Finally, I assume I could just build my own local boost the way I used to build boost's python. But I'd rather use the versions in /usr/local/ lib... shamyl zakariya - squamous and rugose