Hi, This problem has appeared before on the list but in a different context. The following code std::vector<int> myvec; for_each(myvec, std::cout<<_1<<' '); gives the error: Serializer.h:78: error: reference to ‘_1’ is ambiguous /home/sandeep/Computing/boost_1_38_0/boost/lambda/core.hpp:69: error: candidates are: const boost::lambda::placeholder1_type& boost::lambda::<unnamed>::_1 /home/sandeep/Computing/boost_1_38_0/boost/bind/placeholders.hpp:54: error: boost::arg<1> <unnamed>::_1 Serializer.h:78: error: reference to ‘_1’ is ambiguous I believe boost/bind is getting included indirectly via some other library. I have tried several modification but none seem to work as I was quite reluctant to post a third mail on the list. Thanks, sandep