I figured out my problem so please disregard my question. My problem was that zlib and bzip2 support was not being included. I developed a perl script that builds everything for me for Windows & Linux and somehow when the Linux script builds 1.69 or 1.70, it turns off zlib and bzip2 support. Not sure the cause but taking the command my perl script executes and running it the shell outside of perl, boost builds with the proper support for zlib/bzip2 in iostreams. Not sure what the change would be but I have a workaround. wr, Danny