Hi I have build boost libraries for a) regular gcc b) gcc-STLPort the following code works perfectly for "gcc" and throws up the following errors for "gcc-STLPort". // this is my function object that // takes in input parameters as part of its constructor. func_obj instance(data,m_regMap); boost::shared_ptr<thread> pThread(new boost::thread(instance)); ERROR: mystuff.cpp:101: undefined reference to `boost::thread::thread[in-charge] (boost::function0 > const&)' If I assume that the boost runtime library has not been linked, that is not the case.(ldd tells me that i have) whereever I use 'xtime','lock' or 'condition' it doesn't complain. WHAT IS STRANGE IS THE FOLLOWING COMPILES boost::thread thrd; boost::thread thrd(func_obj); // it is the actual fo not an instance. Any help would be greatly appreciated. This happens on Linux/with STLPort 4.6.2/gcc 3.2.3