Hi, The attached test program shows that after a few hundred reloads of a shared library linked with the static build of Boost.Thread, an assert will be raised (gcc 4.4; boost 1.46.1). Does this show a valid bug in a supported usage pattern? ./a.out Call: 0 Call: 100 Call: 200 Call: 300 Call: 400 Call: 500 a.out: /home/sfetche/local/boost/src/boost_1_46_1/boost/thread/pthread/condition_variable_fwd.hpp:46: boost::condition_variable::~condition_variable(): Assertion `!pthread_mutex_destroy(&internal_mutex)' failed. Aborted The test program demonstrates the usage of a shared library that exposes a C interface and is implemented using statically linked Boost libraries. This approach has been taken in order to allow different modules using different versions of Boost to get (re)loaded in the same plugin-based application and has been inspired by this discussion: http://lists.boost.org/Archives/boost/2005/09/94134.php Thank you, Sorin Fetche