I had created a file monitor in March as a reference implementation of how to develop a Boost.Asio extension. While it was pretty incomplete at that time it has become a grown-up and fully tested directory monitor which supports both synchronous and asynchronous I/O. It currently works on Windows only as it is based on Microsoft's I/O Completion Ports (for those who need a directory monitor on Linux see http://article.gmane.org/gmane.comp.lib.boost.asio.user/2699). The directory monitor can be downloaded here: http://www.highscore.de/boost/dir_monitor.zip The zip archive contains various tests which can be used for a quick start. As the directory monitor is pretty small it shouldn't take much longer than 10 minutes to use it in your own projects. Boris