The Dean of the College of Cardinals is the president of the College of Cardinals, in the Catholic Church. He is always a Cardinal of the Holy Roman Church, with the rank and precedence of a sovereign prince and the style of "His Eminence"; according to section 4 of Canon 350 (from the Latin Code of Canon Law 1983), the Cardinal Dean has "the title of the diocese of Ostia, together with that of any other church to which he already has a title". The Cardinal Dean is always of the episcopal order prior to his election as Dean, and continues to hold the title of his former suburbicarian diocese as well as being titular Bishop of Ostia. This has been the case since 1914, by decree of St. Pius X...previous deans since 1150 had given up their prior suburbicarian see for the joint titles of Ostia and Velletri.

Canon 352 is very clear that while the Dean presides over the College of Cardinals (and the sub-Dean in his absence or inability), neither he nor the sub-Dean has any power of governance over the other cardinals. The Dean and sub-Dean are elected by and from among the six cardinal bishops, subject to the approval of the Roman Pontiff (i.e., the Pope).

According to Canon 355, if the newly-elected Supreme Pontiff is not already a bishop, it is the right of the Dean to ordain him as such. If the Dean is unable, then the right falls to the sub-Dean, and then to the senior cardinal of the episcopal order.