The Difference Between a Coadjutor and Auxiliary Bishop

The announcement of Archbishop Gomez’s election as Coadjutor Bishop of the Archdiocese of Los Angeles has many people wondering what a “coadjutor bishop” even is, and how that differs from being an “auxiliary bishop,” or just a plain old (diocesan) bishop. The answer is simple enough:

• Within a given Latin Rite diocese, there is a single diocesan bishop. This is the practice of the Church throughout Her entire history (see, for example, chapter 8 of St. Ignatius of Antioch’s Letter to the Smyrnaeans)
• Since some dioceses are so large that they would effectively impossible to lead single-handedly, auxiliary bishops exist. These men have the full office of bishop: that is, they’re able to ordain men as priests, able to impart the Holy Spirit through the laying on of hands and chrism at Confirmation, and so on. But they don’t have the jurisdiction of an entire diocese. Frequently, the diocesan bishop will assign them to a specific part of the diocese.
• In contrast, the relationship between a diocesan bishop and a coadjutor bishop is the similar to the relationship between a retiring employee who’s training his replacement. The coadjutor bishop has the same authority as the diocesan bishop, but isn’t the diocesan bishop… yet. As I understand it, the diocesan bishop is still the final authority. However, upon the death or retirement of the diocesan bishop, the coadjutor bishop automatically becomes the new diocesan bishop: no need to wait around for the usually protracted process of finding a suitable replacement.

Cardinal Mahoney, in the press conference announcing the appointment of Archbishop Gomez as his coadjutor bishop, described it humorously: Every morning, the auxiliary bishop asks the diocesan bishop, “What can I do for you today?” while the coadjutor bishop asks, “How are you feeling?”