APOSTOLIC PREFECTURE AND APOSTOLIC PREFECT. - The a. p. is an ecclesiastical territory with fixed boundaries, not erected into a diocese, governed by an apostolic prefect. Together with the apostolic vicariate (v.) and the autonomous or sui iuris mission, it forms the territorial missionary organization, also called quasi-diocesan, as a rule directly dependent on the Holy See.
The juridical evolution of this institution has not yet been sufficiently brought to light. Among the Easterners, as may be gathered from the motu proprio Auspicia rerum of Leo XIII, 19 March 1896, and from the decree of the S. Congr. of Prop. Fide, Excelsum, 12 Sept. 1896, there existed a. p.s without a territory of their own within the boundaries of another mission or diocese; among the Latins it is certain that there were a. p.s with a separate territory of their own and juridically independent at least by the middle of the 19th century. The institution is already firmly defined by the end of the 19th century. In the preparatory schemata of the CIC the a. p. appears in perfect parity with the apostolic vicariate, in accordance with what later passed into the CIC itself.
The erection of an a. p. is reserved to the supreme ecclesiastical authority, and its territorial boundaries are not susceptible of prescription; it is usually divided into missionary stations, quasi-parishes and missionary districts; generally it is a completely independent territory, although in practice it is included in a province of missionary law or of common law and therefore subject, in accordance with the CIC, to the jurisdiction of the metropolitan. Its internal regime imitates that of a diocese: the quasi-diocesan curia is formed by the titular, by the delegate vicar, with powers similar to those of the vicar general, and by the Council of the mission, which takes the place of the cathedral Chapter, though with different modalities. The interim regime (vacant and impeded see) is assumed by the pro-prefect, almost in the capacity of a capitular vicar, appointed by the apostolic prefect himself.
When the progress of evangelization is consolidated, the a. p. is elevated to the rank of apostolic vicariate.