I've got a class A that created class Bs class B needs to register callbacks to the class A that created it. So I made member variables in class B that are boost::function type class A binds the method to be called and hands that to class B on construction

So, not class A always has a reference count and cannot be destoryed.

I tried passing a weak_ptr to boost::bind instead and it won't compile.

You can either change your design, so that in one of the directions you pass raw ptr and a weak_ptr for tracking, or take a look at this message: http://permalink.gmane.org/gmane.comp.lib.boost.user/70276