Thanks Igor. I went through the asio reference and did come across post() (event queue like) and dispatch() (blocking direct call like). So this will it then. Further, since io_service's post seems to invoke queued calls in undefined order (could be sequentially as it does presently but reference says not to depend on it), i used strand's post(). I's always a light boost user (only regex and a few others) due to Qt-heavy projects but now have been going through boost's reference pages and sources for over a couple of weeks and must say what superb piece of architecture and concepts ! btw just curious, why didn't you call do_something_sync() directly in post() instead of through a lambda? -- View this message in context: http://boost.2283326.n4.nabble.com/Communication-between-QThread-and-boost-t... Sent from the Boost - Users mailing list archive at Nabble.com.