I've got some code that makes heavy use of mpl. I developed and successfully testid it with msvc8.0 . Then I #included it in a WinForms app (meaning that the compiler is now running with one of the /clr options). The compiler stops with an error explaining that it has "run out of stack space". This could be simply a difference in compiler implementations, but I thought I remembered that mpl was implemented with some builtin recursion unrolling classes to mitigate deeply recursive typedef issues. If so, it occurred to me that maybe the macros mpl is depending on to trigger the level of recursion unrolling aren't supplied when msvc is compiling for CLI. I've perused the code a bit to try to find where it is setting such a thing, but haven't been successful. So I thought I'd post here in hopes of a quick answer. Does mpl implement such a thing? And if so, where is it? I'd like to see if it isn't getting used for cli compilation. Thanks! --Brian