Interoperability is currently seen as one of the most significant problems facing the digital rights management (DRM) industry. In this paper we consider the problem of interoperability among DRM systems from the perspective of a layered architectural framework. The advantage of looking at the problem from this point of view is that the layered framework provides a certain amount of structure that is very helpful in guiding those working on DRM interoperability issues. Specifically, the layered framework we describe provides a useful design abstraction along architectural lines. One of the advantages of this perspective is that it allows us to consider the level within computing/communication architectures at which certain functionality should be provided, and then to address how the functionality between layers should interact in order to provide specific DRM capabilities. The communications that occur between layers, both within a single system and between two communicating systems, are the places where protocols can be defined and possibly standardized. Thus, they provide focal points for studying and addressing interoperability in DRM systems.