Ordination registers have been unduly neglected by historians, and the bibliography ofworks dealing with them is scant. Nevertheless, they are our most valuable source for documenting the recruitment of clergy, both secular and regular, while they also provide indirect evidence for demographic, religious and educational trends. The data assembled in the graphs and tables below, extracted from the archiepiscopal archives of York, detail the total surviving ordination records from England's largest diocese during the period from just before the first outbreak of bubonic plague to the beginning of the Reformation.