In 1045, the northern Iberian Bishopric of Calahorra was brought back into being by García III of Navarre on the frontline of his expanding frontiers with Castile. On the death of its eighth post-restoration bishop in 1190, all or part of the territory of this, by then unmistakably Castilian, see had changed hands no less than seven times between Navarre, Aragon, and Leon-Castile/Castile, as these emergent Christian kingdoms competed furiously over the Riojan frontier zone that it occupied. This book, the first to provide a detailed exploration of eleventh and twelfth century Calahorra, examines the relationship between the extreme volatility of Calahorra’s political situation and the peculiarities of the see’s political and institutional development during its first 145 years as a restored Iberian bishopric.