This thesis aims to define John Calvin's understanding of the relationship between the pastoral and doctoral offices in the Church. The method of inquiry is guided by the proposition that his thinking on this matter is conditioned bythe Patristic and Medieval traditions. Hence, Part One attempts to survey the development of the teaching office in the pre-Reformation Church, giving particular attention to the way in which certain writers deal with this question. Part Two examines the Reformer's doctrine of orders. It is maintained, in opposition to the traditional view of a fourfold division, that Calvin (in line with Patristic andMedieval thinking) consistently taught a threefold division of ecclesiastical orders whereby the doctor ecclesiae is not regarded as holding a separate ordo in the Church's government, but simply a specific function (i.e. "office") withinthe pastoral order. Part Three delineates what; for Calvin, this doctoral function entailed. Again we find the Reformer following his medieval predecessors in strictly identifying the doctor ecclesiae with the doctor theologiae (i.e. scriptural interpretation) and not the university doctorate in general (i.e."all branches of knowledge") as so often supposed. The final section is concerned with demonstrating that even though the Reformer regarded pastors and doctors as comprising only one ordo, he still saw an important difference in their respective teaching ministries in terms of aim, method and authority, as attested to by the distinction he makes between "preaching" the Word and "teaching" the Word.