Digital libraries (DLs) have traditionally been positioned at the intersection of library science, computer science, and networked information systems. The different underlying philosophies of these three fields has had an unsettling influence on the development of DLs. While library science is fairly mature, networked information systems are constantly evolving to keep pace with Internet innovation. DLs are thus expected to demonstrate the careful management of libraries while supporting standards that evolve at an astonishing pace. This architectural moving target is a predicament that all DLs face sooner or later in their lifecycle, and one that few manage to deal with effectively. To exacerbate this problem, there has been a general desire for systems to be interoperable at the levels of data exchange and service collaboration. Such interoperability requirements necessitated the development of standards such as the Dublin Core Metadata Element Set and the Open Archives Initiative's Protocol for Metadata Harvesting (OAI-PMH). These standards have achieved a degree of success in the DL community largely because of their generality and simplicity. Informed by those lessons, this project is an attempt to consistently extend known interoperability standards to form the basis of a framework of components for building extensible DLs.