In Late Antiquity hagiographical literature aimed to memorialize the martyrs’ heroic actions and chronicle the manner in which they endured persecution and met their demise in the name of Christ. In the early Middle Ages the lives of saints emphasized instead the deeds of individuals involved in their own society, particularly those active within the clergy. Thus hagiography proves an invaluable resource to understand the establishment, the functioning, and the transformation of ecclesiastical institutions: monastic communities, bishoprics, sanctuaries, rural churches, and missions. The various rewritings and updatings of some vitae offer a precious vantage point to capture the stages of reform under the early Franks, starting with the great Carolingian reform. To be sure, hagiography did not merely reflect the Church’s organization: it also contributed in its own way to the transformation of ecclesiastical institutions by introducing new norms.