Throughout the later Middle Ages, bishops across western Christendom promulgated legislation to guide the clergy and instruct the faithful within their jurisdictions. Such local ecclesiastical law covered a vast range of topics, from the proper attire of Jews to the punishment of corrupt officials. Until now, however, the extent and dispersion of the surviving sources has made impossible for scholars to explore systematically this legislation, despite its significant impact on European social and religious history. Using a new digital database of this legislation created at Stanford, and drawing on the deep French tradition of scholarship on church history and canon law, our research group aims to study the diffusion, exchange, creation, transformation, and resilience of ecclesiastical norms within the dioceses and provinces of medieval France and its neighbors from 1215-1500. This period witnessed a centralizing effort of unprecedented force within the Catholic Church, as the papacy sought to extend its reach ever further into the affairs of local religious communities. By exploring the scope, mechanisms, rhythms, and limits of legal transfer between ecclesiastical jurisdictions, our research will shed new light on the role played by local legislation in advancing – or resisting – this centralizing effort.