I've recently upgraded to the lastest version of Cygwin and found that this current version supports wchar_t, wstring, etc This section from config/platform/cygwin is now creating problems. // cygwin specific config options: #define BOOST_PLATFORM "Cygwin" #define BOOST_NO_CWCHAR #define BOOST_NO_CWCTYPE #define BOOST_NO_SWPRINTF #define BOOST_HAS_DIRENT_H #define BOOST_HAS_LOG1P #define BOOST_HAS_EXPM1 as it conflits with the following from config/stdlib/libstdcp3 #if !defined(_GLIBCPP_USE_WCHAR_T) && !defined(_GLIBCXX_USE_WCHAR_T) # define BOOST_NO_CWCHAR # define BOOST_NO_CWCTYPE # define BOOST_NO_STD_WSTRING # define BOOST_NO_STD_WSTREAMBUF #endif I've found that BOOST_NO_STD_WSTRING is NOT defined while BOOST_NO_CWCHAR IS defined. This is incorrect for the latest version of cygwin - version 1.7.5 and likely previous versions. I believe that config/platform/cygwin should be updated so that it looks like: #define BOOST_PLATFORM "Cygwin" #define BOOST_NO_SWPRINTF // ? don't know about the rest of these #define BOOST_HAS_DIRENT_H #define BOOST_HAS_LOG1P #define BOOST_HAS_EXPM1 according to the cygwin documentation - there is no place to retrieve a version # for cygwin itself - only for specific packages. So it would seem that that's all we can/should do. Robert Ramey