An apostolic vicariate is led by a vicar apostolic who is usually a titular bishop. While such a territory can be classed as a particular church, according to canon 371.1 of the Latin Code of Canon Law, a vicar apostolic's jurisdiction is an exercise of the jurisdiction of the Pope — the territory thus comes directly under the pope as "universal bishop", and the pope exercises this authority through a "vicar". This is unlike the jurisdiction of a diocesan bishop, whose jurisdiction derives directly from his office.
Like any ecclesiastical jurisdiction, an apostolic vicariate may be administered by the bishop of a neighbouring diocese, or by a priest appointed transitionally as an apostolic administrator. As in a regular diocese, the vicar apostolic may appoint priests as vicars exercising limited jurisdiction over the apostolic vicariate. Normally, however, an apostolic vicariate is administered by a titular bishop of its own. When someone who does not qualify or has not been ordained as bishop is appointed ad interim, he may be styled Pro-apostolic vicar.
An apostolic vicariate is to be distinguished from an apostolic prefecture, a similar type of territory whose chief distinction from an apostolic vicariate is that its prefect is not a titular bishop, but a mere priest. The latter is not organised enough to be elevated to apostolic vicariate. The less developed instance is the mission sui iuris, which other than the ones mentioned before is not a particular church, although it shares some similarities to one; at its head, an ecclesiastical superior is named. The usual sequence of development is mission, apostolic prefecture, apostolic vicariate and finally diocese (or even archdiocese). See also apostolic exarch for an Eastern Catholic counterpart.
Inactive apostolic vicariates (and/or former names, often promoted to diocese) are in italics. Eastern Catholic (mostly Byzantine Rite) apostolic vicariates are in bold.