Each of the dioceses is divided into a number parish groups.

The three dioceses of Kilmore, Elphin and Ardagh were first created in the early and mid 12th-century.

The sees of Elphin and Ardagh were established at the Synod of Rathbreasail in 1111 and the see of Kilmore (originally called Tirbrunensis, Triburnia or Tybruinensis) at the Synod of Kells in 1152.

The English-speaking minority [citation needed] mostly adhered to the either the Church of Ireland or, despite the political and economic advantages of membership in the state church, to Presbyterianism.

The Diocese of Kilmore, Elphin and Ardagh is theologically conservative.