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, it is often not called after such city but rather after a natural or administrative (in many cases colonial) geographical area.
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.
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.
A prefect apostolic is of lower rank than a vicar apostolic. The prefect's powers are more limited and do not normally possess the episcopal character, as is ordinarily the case with a vicar apostolic. The duties of a prefect apostolic consist in directing the work of the mission entrusted to his care; his powers are in general those necessarily connected with the ordinary administration of such an office, for instance: the assigning of missionaries and the making of regulations for the good management of the affairs of the mission. Until the Second Vatican Council, the prefect apostolic had extraordinary faculties for several cases reserved otherwise to diocesan bishops, such as absolutions from censures, dispensations from matrimonial impediments and the faculty of consecrating chalices, patens, and portable altars, with some having the power to administer Confirmation.
Prefects apostolic govern independent territories and are subject only to the pope. When a vicariate or a diocese extended over a very large territory in which the Catholic population was unequally distributed, the Holy See sometimes placed a portion of the territory in charge of a prefect apostolic; in which case the faculties of the prefect were more limited, and in the exercise of his office he was supervised by the vicar apostolic or the diocesan bishop. With a view to better protecting the authority of the local vicar apostolic or bishop, it was proposed in the First Vatican Council to abolish prefects apostolic having jurisdiction over districts within a vicariate or diocese of the Latin Rite, but the Council was interrupted and the practice continued until Pope Leo XIII abolished them within the Oriental Churches by a decree of Propaganda Fide on 12 September 1896, and established superiors with special dependence on the papal representatives of the areas concerned.
In 1911 there were 66 prefectures apostolic: 5 in Europe; 17 in Asia; 3 in North America (e.g., the Yukon); 11 in South America; 23 in Africa and 7 in Oceania.
At the end of 2010, the prefectures apostolic were only 39, of which the vast majority (29) were in PR China (many vacant), where development of the Catholic Church, including that of the prefectures, had long been hindered by actions of the government. The 10 other prefectures included a newly created one for Azerbaijan, 4 more in Asia, 3 in Africa, 1 in the Americas and 1 in Oceania.
Most former apostolic prefectures were promoted to apostolic vicariate or territorial prelature (under a titular bishop) or (mostly later) to a diocese or even an archdiocese (under a residential bishop), but some ceased to exist (at least under their name or extent) being suppressed or sometimes dismembered.