This is a comprehensive list of Catholic dioceses in the island of Ireland. Catholicism in Ireland only maintains a Latin Church hierarchy, encompassing both the Republic of Ireland and Northern Ireland, having been unaffected by the partition of Ireland in 1920–22. There are no Eastern Catholic jurisdictions, nor other exempt ordinariates.
There are 26 dioceses in Ireland, each led by a diocesan bishop (including four Metropolitan Archdioceses). They are organised into a single all-island Episcopal Conference that is based in the primatial see of Armagh. The Holy See is represented by the Apostolic Nuncio to Ireland. A separate Apostolic Nunciature in London represents the Holy See in England, Wales and Scotland.
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.
The Roman Catholic dioceses remained close to the original, with a few notable differences. Firstly, several dioceses with small populations were merged, and now have more than one name to represent their merger. Secondly, the Diocese of Galway was created in 1831 following the abolition of the Wardenship of Galway.
James Butler 2nd, the Archbishop of Cashel and Emly (1774–91),[1] on being appointed by Rome moved his residence and cathedra from Cashel, favouring Thurles instead, where his successors continue to reign today. Similarly, in the Diocese of Elphin, the Cathedral, which was originally established in the County Roscommon town of Elphin, is now in Sligo.
Another change is that the ancient see of Kilfenora has been administered by the Bishop of Galway in the province of Tuam since the late 19th Century. The correct title of the Bishop is now the Bishop of Galway and Kilmacduagh and Apostolic Administrator of Kilfenora. More recently, the Diocese of Ross merged with the Diocese of Cork to form the Diocese of Cork and Ross in the 1950s.
Unlike many (European) countries, the boundaries of the Roman Catholic dioceses in Ireland do not conform with the political border between the Republic of Ireland (independent) and Northern Ireland (part of the UK). One archdiocese and three dioceses straddle the international border; two dioceses are wholly in Northern Ireland.
Approximating the civil province of Ulster; mainly in Northern Ireland.
Approximating the civil province of Munster.
Approximating the civil province of Leinster.
Approximating the civil province of Connacht.
As the Diocese of Kilfenora is in the Ecclesiastical province of Cashel, the Bishop of Galway and Kilmacduagh is its apostolic administrator rather than bishop.
There are seventeen titular sees in Ireland (of which two are united in personal union with current sees): Ardcarne, Ardmore, Ath Truim, Ceanannus Mór, Cell Ausaille, Cill Fhionnúrach (united with Galway and Kilmacduagh), Clonmacnoise (united with Diocese of Ardagh), Cluain Iraird, Cunga Féichin, Domnach Sechnaill, Duleek, Eanach Dúin, Glenndálocha, Inis Cathaig, Louth, Mageó, Roscrea, Slebte, Árd Sratha (formerly as Ardstraw an abbey nullius becoming a diocese, merged into Diocese of Cinél nEógain and Ardstraw; territory now in diocese Derry).