Hi! I am pretty sure this is an issue beyond boost, rather one of those numerous pitfalls on the way to the M$-promised land called CanUseOldCodeAndCppInDotNet. OTOH I have hope that someone knows about some workaround, OK, here the facts: Win32, XP SP3, using Visual Studio 2008 SP1 with boost_1_37_0 I create a solution containing a C++/CLI project and a C# project, which references the C++/CLI project. Now if the C++/CLI project simply links to libboost_thread*, either via autolink or via explicit configuration, the compiler creates an executable which fails to start in both configurations, Debug and Release. The debugger catches a System.BadImageFormatException. Something went plain wrong. OTOH adding the source files contained in \libs\thread\src\win32 to the project, defining BOOST_ALL_NO_LIB and adding --- #pragma managed(push, off) extern "C" void tss_cleanup_implemented(void) {} #include <boost/thread/thread.hpp> #pragma managed(pop) --- in a cpp file yields a working executable. Scratching my head. Do you have any hint why linking to libboost_thread leads to this weird behaviour? Any idea what I might try? I can provide a stripped down project solution as zip-file on request. regards, Markus [keywords C# C++/CLI CSharp mixed thread boost System.BadImageFormatException]