Hi, Sorry to disturb the list but I've been stuck with this problem for a while. The idea is to pass the reference of some data object to the thread function, in which the data object (by which the ref is passed in) will be modified. However I have found that this would not work at run-time, as the program compiled, ran but the modifying code silently failed to execute. I've written a small sample, which is self-contained and compilable: // // File: thread_test.cc // Author: xli // // Created on December 26, 2007, 12:26 AM // #include #include #include <iostream> #include <vector> using namespace std; int s_count = 0; boost::mutex mutex; struct some_data_t { some_data_t() : m_int(0) {} int m_int; vector<int> m_vec; }; class threaded { public: void increment_count( some_data_t& data ) { boost::mutex::scoped_lock lock(mutex); std::cout << "count = " << ++s_count << std::endl; data.m_int += s_count; data.m_vec.push_back(s_count); } }; some_data_t a; int main(int argc, char* argv[]) { threaded _thrd; boost::thread_group threads; for (int i = 0; i < 10; ++i) threads.create_thread( boost::bind( boost::mem_fn( &threaded::increment_count ), &_thrd, a ) ); threads.join_all(); cout <<"All done. " <