Hi, I built my boost on Mac OSX 10.8 as follows: ./bootstrap.sh -prefix=/users/tim/developer/libraries/boost_1_50_0/stage ./b2 -address-model=32_64 stdlib=libc++ This ran boost.build with the Darwin toolset, as expected, and generated no errors. Checking the stage/lib folder revealed a complete set of static and dynamic library files with appropriate date-time stamps. I specified the linker as libc++ as the project I'm working on using XCode 4.6 uses wxWidgets 2.9.4, which requires that the project be compiled using Apple's GCC instead of the default compiler (this, in turn, means that libc++ becomes the linker used by the project). However, when I try to build my XCode project, I get errors of the form: Undefined symbols for architecture x86_64: "boost::archive::basic_xml_iarchive<boost::archive::xml_wiarchive>::load_sta rt(char All of the errors refer to boost::archive or boost::serialisation. My project also uses the boost FileSystem, IOStream and System libraries, which don't generate any errors. I've found an awful lot of references to this issue on the web (particularly StackOverflow), but have yet to find an answer/solution. I'm pretty sure that I'm using the correct command-line options (I didn't specify architecture=combined, as Mac OSX SDK 10.8 no longer supports PPC), but I'm confused by the plethora of available build options, as I'm a novice on this platform. The project is a cross-platform effort and the same source code presented to my Windows VS2010 32/64-bit project builds and runs. Similarly, the same project built and ran under Mac OSX 10.6 with XCode 3.6 - I'd gladly revert to the older Mac O/S and XCode except for the fact that I'm a blind developer and the debugger provided in XCode 3.6 is not accessible to me using Apple's VoiceOver speech output utility (the debugger in XCode 4.6 holds out more hope for being usable). I'd greatly appreciate any tips and tricks for resolving this problem, so many thanks in advance. Best wishes. Tim Burgess Raised Bar Ltd. Tel: +44 (0)1827 719822 Web: http://www.raisedbar.net We can supply Roland and Avid products with specialist pre and post-sales support for visually-impaired users - just drop us a line for a quote. Don't forget to sign our on-line petition to lobby for improved access to music education and music technology at: http://www.raisedbar.net/petition.htm