It seems is not included in the files you can download from http://spirit.sourceforge.net/dl_more/fusion_v2/ In particular I'm looking for #include <boost/fusion/functional/invocation/invoke_procedure.hpp> BTW fusion 2 is not bundled with the boost_1_34_1.tar.bz2 you get from sourceforge, so to be able to have a complete fusion library an user is supposed to walk: boost.org --> download boost_1_34_1.tar.bz2 from sourceforge --> (surprise! fusion is not in) --> google ---> spirit.sourceforge.net/dl_more/fusion_v2/ ---> (surprise! functional module is not in) ---> google again ----> pain!! -> ask to mailing list ---> ??? Not exactly what you would call "user friendly".... Interesting enough the corresponding documentation is much easier to find: http://spirit.sourceforge.net/dl_more/fusion_v2/libs/fusion/doc/html/index.h... Thanks for any help to find this well hidden link. Marco