Since both I and Andreas are baffled by this problem, I thought I'd forward this on to the larger Boost community. Anyone have any ideas about it? It seems like it should be a simple thing but something about the way lookup works in C++ is causing the inner_context_type member of simple_state to be missed. The problem persists even if typedef typename sc::simple_state< NormalMode< Type >, Switch, Off<Type> >::inner_context_type inner_context_type; is added to the NormalMode class template. -Dave