List of Roman Catholic dioceses in Ireland

This is a comprehensive list of Roman Catholic dioceses in the island of Ireland. Roman Catholicism in Ireland is organised as a single Episcopal Conference encompassing both the Republic of Ireland and Northern Ireland, having been unaffected by the partition of Ireland in 1920–22. There are in total 26 dioceses in Ireland, each led by a diocesan bishop.

The diocesan system of Christian church government in Ireland was set up by the Synod of Rathbreasail in 1111 and modified by the Synod of Kells in 1152, replacing the earlier Celtic Christian monastic model. The island of Ireland is divided into four ecclesiastical provinces each headed by a metropolitan archbishop. The provinces were almost co-extensive with their contemporary civil counterparts. After the Reformation in Ireland, both the Protestant Church of Ireland and the Roman Catholic Church saw themselves as successors to the pre-Reformation church. Most bishops were non-resident during the enforcement of the Penal Laws, but the dioceses continued to exist. Whereas English Catholic dioceses were forbidden by law from having the same name as a diocese of the established Church of England, no such prohibition was made for Irish dioceses.

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