Les, everyone is correct in stating there are inherent problems (or issues to be aware of) with multiple inheritance. However, it is certainly handy when you really need it (and know what to be careful of). Again, feel free to check out the inheritance model I use ( http://www.someelement.com/2007/03/multiple-inheritance-with-prototypejs.html), as it does support multiple inheritance as well. There are also some issues I have with the whole "prototype-static, instance" methods vs. "true instance only" methods, so I do away completely with forcing references to the superclass methods. You need to call a superclass method within an overridden subclass method - just grab the reference on your own (explained in that blog post).