Heres another combination of many things I've been trying, but still cant get this to work. Unfortunately, this only works once, meaning it only receives one dir_monitor callback event, and if I cause another same event in a monitored directory, the f_handler() callback will no longer get called. I am able to post from thread1 to thread2 or from thread1 to the main process, but that also only works one time. Any ideas? --- boost::asio::io_service service1; boost::asio::io_service service2; // dir_monitor callback running in thread 1 void f_handler(const boost::system::error_code &ec, const boost::asio::dir_monitor_event &ev) { TaskObj tsk = new TaskObj(...); // detect event, create task and post functor to thread 2 which handles tasks service2.post(boost::bind(&TaskObj::do_it, tsk)); } int main(...) { boost::asio::dir_monitor dm(service1); for (/*directory list*/) { dm.add_directory(dir); } dm.async_monitor(f_handler); // setup work to prevent exit and before running io_service shared_ptrboost::asio::io_service::work work(new boost::asio::io_service::work(service)); // thread to constantly monitor dirs boost::thread t1 = boost::thread(boost::bind(&boost::asio::io_service::run, boost::ref(io_service))); t1.detach(); // thread to do tasks as posted by dir_monitor thread and idle if no tasks exists boost::thread t2(boost::bind(&boost::asio::io_service::run, boost::ref(work_service))); t2.detach(); while (true) { // do other stuff or idle, don't want main process to exit. }