Jeff, I've been playing with date_time to try and get it to do the right thing with VC++ when /Zc:wchar_t is *not* specified, and I've come up with a list of questions for you if you don't mind :-) 1) What's the meaning of USE_DATE_TIME_PRE_1_33_FACET_IO? Without it the testtime_wstream.cpp test case fails even with /Zc:wchar_t, this is a source of confusion if you're building the building the tests in your IDE for whatever reason. 2) Without USE_DATE_TIME_PRE_1_33_FACET_IO the testgrep_wstream.cpp test doesn't compile irrespective of the /Zc:wchar_t option: testgreg_wstream.cpp c:\data\boost\develop\boost\boost\date_time\date_facet.hpp(640) : error C2678: binary '+' : no operator found which takes a left-hand operand of type 'const char [35]' (or there is no acceptable conversion) c:\data\boost\develop\boost\boost\date_time\date_facet.hpp(606) : while compiling class-template member function 'std::istreambuf_iterator<_Elem,_Traits> boost::date_time::date_input_facet<date_type,CharT>::get(InItrT &,InItrT &,std::ios_base &,boost::date_time::date_input_facet<date_type,CharT>::duration_type &) const' with [ _Elem=wchar_t, _Traits=std::char_traits<wchar_t>, date_type=boost::gregorian::date, CharT=wchar_t, InItrT=std::istreambuf_iterator<wchar_t,std::char_traits<wchar_t>> ] c:\data\boost\develop\boost\boost\date_time\gregorian\gregorian_io.hpp(78) : see reference to class template instantiation 'boost::date_time::date_input_facet<date_type,CharT>' being compiled with [ date_type=boost::gregorian::date, CharT=wchar_t ] c:\data\boost\develop\boost\libs\date_time\test\gregorian\testgreg_wstream.cpp(50) : see reference to function template instantiation 'std::basic_istream<_Elem,_Traits> &boost::gregorian::operator

...

<wchar_t,std::char_traits<wchar_t>>(std::basic_istream<_Elem,_Traits> &,boost::gregorian::date &)' being compiled with [ _Elem=wchar_t, _Traits=std::char_traits<wchar_t> ]

3) Finally there are a lot of places where an unsigned short is written to or read from a stream: unfortunately the dinkumware lib treats these "as if" they were a wide character value, rather than an integer. Casting to unsigned int in these cases would fix that, but it's a horrid cludge, and I don't know what you might think about that! Thanks, John.