Mission Prefecture

An apostolic prefect or prefect apostolic is a priest who heads what is known as an apostolic prefecture, a 'pre-diocesan' missionary jurisdiction where the Catholic Church is not yet sufficiently developed to have it made a diocese. Although it usually has an (embryonal) see, sometimes even a cathedral it is often not called after such city but rather after a natural and/or administrative (in many cases colonial) geographical area: region(s), sometimes a country or even larger.

If a prefecture grows and flourishes, it may be elevated to an apostolic vicariate, headed by a titular bishop, in the hope that with time the region will generate enough Catholics and stability for its Catholic institutions, to warrant being established as a diocese. Both these stages remain missionary, hence exempt, i.e. directly subject to the Holy See (notably the Roman Congregation for the Evangelization of Peoples), normally not part of an ecclesiastical province.

The full sequence of development is: independent mission, apostolic prefecture, apostolic vicariate, apostolic diocese; however steps may be skipped at the papal discretion, so the next steps may be bishopric or even archbishopric.

The apostolic prefecture and the apostolic vicariate are to be distinguished from the territorial abbacy (formerly called an "abbey nullius").

During the last centuries of the second millennium it was the practice of the Holy See to govern either through prefects apostolic or apostolic vicariates, many territories where no dioceses with resident bishops were erected and where local circumstances, such as the character and customs of the people or hostility of civil powers, made it doubtful whether an episcopal see could be permanently established. The establishing of a prefecture apostolic in a place supposes that the Church has attained only a small development in the area. Fuller growth leads to the foundation of an apostolic vicariate as an intermediate stage to becoming a diocese.

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Wikipedia