An ecclesiastical province is one of the basic forms of jurisdiction in Christian churches, including those of both Western Christianity and Eastern Christianity, that have traditional hierarchical structures. An ecclesiastical province consists of several dioceses (or eparchies), one of them being the archdiocese (or archeparchy), headed by a metropolitan bishop or archbishop who has ecclesiastical jurisdiction over all other bishops of the province.

In the Greco-Roman world, ecclesia (Ancient Greek: ἐκκλησία; Latin: ecclesia) was used to refer to a lawful assembly, or a called legislative body. As early as Pythagoras, the word took on the additional meaning of a community with shared beliefs. This is the meaning taken in the Greek translation of the Hebrew Scriptures (the Septuagint), and later adopted by the Christian community to refer to the assembly of believers.

In the history of Western world (sometimes more precisely as Greco-Roman world) adopted by the Roman Empire and the Byzantine Empire, Christian ecclesiastical provinces were named by analogy with the secular Roman province as well as certain extraterritorial formations of the western world in early medieval times (see Early Middle Ages). The administrative seat of each province is an episcopal see. In hierarchical Christian churches that have dioceses, a province is a collection of those dioceses (as a basic unit of administration).

Over the years certain provinces adopted the status of metropolis and have a certain degree of self-rule. A bishop of such province is called the metropolitan bishop or metropolitan. The Catholic Church (both Latin and Eastern Catholic), the Orthodox Churches and the Anglican Communion all have provinces. These provinces are led by a metropolitan archbishop.^{[citation needed]}

Ecclesiastical provinces first corresponded to the civil provinces of the Roman Empire. From the second half of the 2nd century, the bishops of these provinces were accustomed to assemble on important occasions for common counsel in synods. From the end of that century the summons to attend these increasingly important synods was usually issued by the bishop of the capital or metropolis of the province, who also presided over the assembly, especially in the East. Important communications were also forwarded to the bishop of the provincial capital to be brought to the notice of the other bishops. Thus in the East during the 3rd century the bishop of the provincial metropolis came gradually to occupy a certain superior position, and received the name of metropolitan.

At the First Council of Nicaea (325) this position of the metropolitan was taken for granted, and was made the basis for conceding to him definite rights over the other bishops and dioceses of the state province. In Eastern canon law since the 4th century (cf. also the Synod of Antioch of 341, can. ix), it was a principle that every civil province was likewise a church province under the supreme direction of the metropolitan, i.e. of the bishop of the provincial capital.

This division into ecclesiastical provinces did not develop so early in the Western Empire. In North Africa the first metropolitan appears during the 4th century, the Bishop of Carthage being recognized as primate of the dioceses of Northern Africa; metropolitans of the separate provinces gradually appear, although the boundaries of these provinces did not coincide with the divisions of the empire. A similar development was witnessed in Spain, Gaul, and Italy. The migration of the nations, however, prevented an equally stable formation of ecclesiastical provinces in the Christian West as in the East. It was only after the 5th century that such gradually developed, mostly in accordance with the ancient divisions of the Roman Empire. In Italy alone, on account of the central ecclesiastical position of Rome, this development was slower. However, at the end of antiquity the existence of church provinces as the basis of ecclesiastical administration was fairly universal in the West. In the Carolingian period they were reorganized, and have retained their place ever since.

In the Catholic Church, a province consists of a metropolitan archdiocese and one or more (1–13) suffragan dioceses headed by diocesan bishops or territorial prelatures and missions sui iuris. The archbishop of the metropolitan see is the metropolitan of the province. The delimitation of church provinces in the Latin Church is reserved to the Holy See.