Hi Jeffrey, In my experience, changing the class layout based on a preprocessor switch is a very bad idea since it breaks binary compatibility with libraries compiled with a different switch, so I strongly suggest you/we find a better solution. If this functionality is really really needed (read below), I would create a *different* template class to offer it. One such debugger-friendly optional<> would replace (rather than add) the bool field with a T* field (which would be set to NULL when uninitialized). A different template class makes sure that binary-differing optional's don't mix accidentally (in the same wa a policy-based design does it). But I'm curious: doesn't a simple dynamic watch, like "*opt", works?? That calls a method on the object, yes, but debuggers have been able to do that for decades now. Or perhaps your problem is that you don't want to be watching/inspecting "*opt" manually? I'm using C# a lot lately and it has a nice feature: the debugger automatically calls .ToString() on any variable it shows. That's *so* useful. Doesn't VC++ has some sort of similar mechanism? Best -- Fernando Cacciola SciSoft http://fcacciola.50webs.com