I'm using Boost 1.37 and I've found that using the headers to develop WinCE applications with WinCE causes Boost header config/compiler/visualc.hpp to emit the EVC++ version not recognized. I've patched the *visualc.hpp* header to recognize the WinCE/VC9 configuration as follows: (line 150): # if defined(UNDER_CE) # if _MSC_VER < 1200 // Note: these are so far off, they are not really supported # elif _MSC_VER < 1300 // eVC++ 4 comes with 1200-1202 # define BOOST_COMPILER_VERSION evc4.0 # elif _MSC_VER == 1400 # define BOOST_COMPILER_VERSION evc8 *# elif _MSC_VER == 1500 # define BOOST_COMPILER_VERSION evc9* # else # if defined(BOOST_ASSERT_CONFIG) # error "Unknown EVC++ compiler version - please run the configure tests and report the results" # else # pragma message("Unknown EVC++ compiler version - please run the configure tests and report the results") # endif # endif Thanks, I dont if there's any workaround already available. Hernán.