Hello, I'm an enthusiastic and grateful user of boost (multi_index_set, accumulators, much else), so first thanks a lot to you all. But I can't get program_options/example/first.cpp to compile. I am sure it's something simple I've missed, but I can't tell what. I am running boost 1.40, gcc version 4.0.1, on a new iMac. output: cc -g -o test obj/pgmopts.o -lstdc++ Undefined symbols: "boost::program_options::detail::cmdline::run()", referenced from: boost::program_options::basic_command_line_parser<char>::run () in pgmopts .o "boost::program_options::options_description_easy_init::operator() (char const* , boost::program_options::value_semantic const*, char const*)", referenced from: _main in pgmopts.o "boost::program_options::validation_error::what() const", referenced from: vtable for boost::exception_detail::error_info_injector<boost::program_opt ions::invalid_option_value>in pgmopts.o vtable for boost::program_options::invalid_option_valuein pgmopts.o vtable for boost::exception_detail::clone_impl<boost::exception_detail::er ror_info_injector<boost::program_options::invalid_option_value> >in pgmopts.o ... Help! and thanks again.