This is a study of the caliphate as a political institution in Islamic Spain, from its inception in 316/939 until the disappearance of the Umayyads in Cordoba in 422/1031. David J. Wasserstein explores the caliphal claims of the Hammudid dynasty in the south of the peninsula, and examines the caliphal practices of two Slav rulers of the eleventh century. He shows that the caliphal insitution was not abolished at any stage, and that it served rulers throughout the eleventh century as, among other things, an important source of legitimacy.Professor Wasserstein's important new interpretation is thoroughly grounded not only in the documentary sources, but also in the little-studied and revealing numismatic evidence. This is a significant contribution both to the Islamic history of the Iberian Peninsula and to our understanding of the nature of the caliphate within Islam in general.