Hi, I'm using Boost to build projects for the Mac. What I don't understand is how to build the libraries to support previous Mac OSX SDK versions. I'm having to build using XCode 4.5 on Mountain Lion (10.8), but want to ensure that my projects will run on 10.7 as a minimum. All advice gratefully accepted. Best wishes. Tim Burgess Raised Bar Ltd. Tel: +44 (0)1827 719822 Web: http://www.raisedbar.net