Because version 3 will break some user code, both v2 and v3 will be shipped for several releases. For 1.44, the default is v2 and the user has to explicitly switch to v3. I'd really appreciate it if some Boosters could give v3 a try on your own code that uses Boost.Filesystem. If you already have trunk on your machine, just run "svn up" on it. Otherwise, checkout a copy: mkdir boost-trunk svn co http://svn.boost.org/svn/boost/trunk boost-trunk If you prefer, "svn export http://svn.boost.org/svn/boost/trunk boost-trunk" should also work. Then read boost-trunk/libs/filesystem/dual_versions.html, and follow the instructions there. Then please let me know your results: * Are the instructions for changing to version 3 sufficient? They are pretty minimal, but I'm assuming those doing this have a high level of background knowledge. * Did you have any problem changing to version 3? * Did you have problems compiling your code against version 3? * If there were compile errors, do you have any ideas about how to mitigate the problem? * Did you have any problems testing or running your code with version 3? * Any other comments or suggestions? Thanks, --Beman