This thesis studies the collections of saints' relics preserved in English religious houses during the Middle Ages. It is based upon an examination of as many lists of relics compiled in these houses as it has been possible to find, together with such related material as is available. The first chapter discusses the attitude of medieval people towards relics in general, and also the present state of study of the subject of relic-veneration and the principles of this inquiry. All the available relic lists are then examined in turn, according to the type of religious house where they originated. In each case, an attempt is made to trace the development of the collection, by determining as far as the evidence permits, when and how it was built up and who were the leading figures in this process. Notice is taken where indications emerge of the many and varied purposes which relics served in the lives of the communities which preserved them and of society in general. The final chapter attempts to explain the fundamental importance by arguing, on the basis of the evidence presented, that each religious house's collections was in a sense, an expression of its own identity. Among the appendices a catalogue of relic lists sets outs as many lists, printed and unprinted, as it has been possible to discover and an index of Saints uses the information given in them to define the relic cults of individual saints in England, by establishing which list claimed relics of each saint. The texts of some important unprinted lists are given in a further appendix.