I believe that there is no reason why BOOST_NO_INTRINSIC_WCHAR_T should be taken into account when defining DISABLE_WIDE_CHAR_SUPPORT at the beginning of lexical_cast.hpp file. The fact that on some platform wchar_t is not builtin type (as it should be) but some typedef (e.g. to short), should not disable wchar_t support in lexical_cast. If platform does not have any support for wchar_t then other macros (e.g. BOOST_NO_STD_WSTRING) will be defined, leading to definition of DISABLE_WIDE_CHAR_SUPPORT. On the other hand, if some platform emulates wchar_t and has decent support for wide strings, wide streams etc, then there is no real reason to disable lexical_cast support for wchar_t on such platform. My coleague was just bitten by this when trying to use lexical_cast on MSVC6:

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citation begin Using Microsoft Visual Studio 6 and DinkumWare 2.3 Standard library, I was prevented from using lexical_cast with wide strings. The BOOST_NO_INTRINSIC_WCHAR_T was defined, which prevents the wide character parts of lexical_cast from being compiled. Reading the documentation on BOOST_NO_INTRINSIC_WCHAR_T, it would seem that this was not used appropriately in lexical_cast.hpp

By removing the line from lexical_cast.hpp I was able to successfully compile and use lexcical_cast with wstring. Modified lexical_cast.hpp. In this section : #if defined(BOOST_NO_STRINGSTREAM) || \ defined(BOOST_NO_STD_WSTRING) || \ defined(BOOST_NO_STD_LOCALE) || \ defined(BOOST_NO_INTRINSIC_WCHAR_T) removed || \ defined(BOOST_NO_INTRINSIC_WCHAR_T)

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I hope that our findings are correct and this can be fixed in release 1.33 . Regards B.