The Church of England continued this diocesan structure after the Reformation.
In the later organization of the Roman Empire, the increasingly subdivided provinces were administratively associated in a larger unit, the diocese. (Latin dioecesis, from the Greek term διοίκησις meaning "administration").
The Catholic Church adopted the Roman diocesan structure of authority during the 5th and 6th centuries, as each bishop fully assumed the role of the former Roman praefectus. This transfer of authority from secular officials to ecclesiastical leaders was facilitated by the Christian practice of establishing areas of ecclesiastical administration that coincided with those of the Roman civil administration. In modern times, many an ancient diocese, though later divided among several dioceses, has preserved the boundaries of a long-vanished Roman administrative division. See also: Bishops and civil government.
The reorganization of the Empire known as Tetrarchy began under Emperor Diocletian, who divided the vast Empire into four quarters, originally each under a co-emperor ('Tetrarch') but as these soon were abolished under their former chiefs of staff, styled pretorian prefects, who had authority over the next, also new administrative level: twelve dioceses. The largest, Oriens, included sixteen provinces, and the smallest, Britain, was comprised of only four provinces. A list of Roman dioceses as they existed in 395 CE can be found at the entry for Roman provinces.
Each diocese of the Empire was governed by a vicarius . Between the 4th and 6th centuries, as the older administrative structure began to crumble, the role of the bishops in the western lands of the Empire enabled those lands and their peoples to maintain a semblance of civilisation as the authority of Rome vanished. The senatorial aristocracy, especially in the provinces, continued in many places to serve as sources of local authority to complement the authority assumed by the Church. At that time, ecclesiastical political power was often vested in the spiritual offices of the bishops in each region. It is, therefore, unsurprising that, as the Catholic, and later the Eastern Orthodox, churches began to define their respective administrative structures, they relied on the older Roman terminology and methods to describe administrative units and hierarchy, which caused the division between ecclesiastical and secular authority to often disappear. In the Eastern Empire, this became fundamental doctrine: see Caesaropapism.
In English-speaking countries, The Church of Jesus Christ of Latter-day Saints uses the term ward, rather than parish, to refer to the jurisdiction of the bishop and his counselors. However, the ward is not equal in size to a Catholic diocese; rather, a stake is.
Christian group structuring | Episcopacy in Anglicanism
Diosez | Diòcesi | Diecéze | Stift | Diözese | Diócesis | Diocèse | Diocese | Dijeceza | Diocesi | דיוקסיה | Episcopatus | Vyskupija | Bisdom | 教区 | Egyházmegye | Bispedømme | Bispedøme | Diecezja | Diocese | Dieceză | Škofija | Stift (kyrkligt förvaltningsområde) | Єпархія | 教區