Doug Gregor has indicated to me that he is not able to continue with the development/maintenance of Boost.Signals. [ This is not a surprise, the last significant change to the library was back in 2004. ] Fortunately, Frank Hess' Signals2 library is going strong, and he has a porting guide for people currently using Boost.Signals at: http://www.boost.org/doc/html/signals2/api_changes.html#signals2.porting For the upcoming 1.54 release, I have added notes to this effect to the Boost.Signals documentation, and added a warning to . The warning states: Boost.Signals is no longer being maintained and is now deprecated. Please switch to Boost.Signals2. To disable this warning message, define BOOST_SIGNALS_NO_DEPRECATION_WARNING Note: There have been no code changes to Boost.Signals. All code that uses it will continue to work. -- Marshall Marshall Clow Idio Software mailto:mclow.lists@gmail.com A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki