After the reform of the Irish Church in the twelfth century from a monastic to a diocesan structure, religious orders were encouraged to set up houses in Ireland to facilitate this process. A number of early monastic sites in Mayo, including Cong, Ballintober, Mayo, Inishmaine and Errew, were occupied and developed as abbeys for Canons Regular of Saint Augustine under the patronage of Gaelic families such as the O’Connors in the twelfth and thirteenth centuries. The best-known abbey in Mayo, and one of the most famous in Ireland, is Ballintober, where Mass has been said without a break since its foundation in 1216. These Canons Regular of St Augustine were distinct from the later order of Augustinian friars (OSA). Their Canons’ regulations were introduced to Ireland by St Malachy of Armagh about 1140, who wanted to end the isolationism of the Irish church and link it with the universal church in Rome. He was also responsible for the Cistercians establishing their first Irish foundation at Mellifont, County Louth, in 1142. They established an abbey at Knockmoy in County Galway in 1189, with a subordinate foundation on Clare Island at the entrance to Clew Bay in County Mayo in 1224. The Cistercians were supported by benefactors.
Most new religious communities established in Ireland from the early thirteenth century onwards were mendicant friars, who begged for alms to supplement their incomes. Friaries were established in County Mayo by the four main mendicant orders, Dominicans, Carmelites, Franciscans and Augustinians, with the support of both Anglo-Norman and Irish families. The Dominicans started in Ireland in 1224, and were thus the first of the mendicant orders to be established here. The first Mayo friary was established at Straide for the Franciscans between 1240 and 1250, but it was transferred to the Dominicans in 1252. The Dominicans also established a friary at Rathfran, near Killala, around 1274. Around 1434, the Mac Costellos established the Dominicans at Urlaur in the parish of Kilmovee, with another house founded at Burrishoole, near Newport, around 1486. The Carmelite order, was instituted in Ballinsmaula, near Claremorris, around 1288 under the patronage of the Prendergasts. The Carmelites established a foundation at Burriscarra, near Ballinrobe, in 1298 with the support of the Stauntons, but it was abandoned after about eighty years, and later taken over by the Augustinian Friars.
The First Order of Franciscans was for friars, the Second Order for nuns, with the Third Order for lay men and women. The Franciscans started in Ireland around 1230. After establishing a friary at Straide in the 1240s, which (as mentioned above) was transferred to the Dominicans in 1252, they had no presence in Mayo until the fifteenth century. Rosserk Friary, beside Killala Bay, was founded about 1441 for the Franciscan Third Order, and Moyne Friary, nearby, for regular Franciscan friars around 1455.
The Augustinian Friary in Ballinrobe, established about 1312, was the first of their nine foundations in Connacht, including four others in County Mayo: Ardnaree, Ballyhaunis, Burriscarra (after its abandonment by the Carmelites) and Murrisk. The Augustinians developed a friary at Ardnaree about 1400 with the support of the O’Dowds, and the Mac Costellos established them in Ballyhaunis around 1430. Murrisk Friary, overlooking Clew Bay, was started about 1456 by the O’Malleys. After the dissolution of the abbeys and friaries in Mayo during the Reformation in the sixteenth century, many of the new owners of confiscated religious property allowed the friars to return and continue their work. The foundations just mentioned were all attractive buildings, with the surviving structures still impressive archaeological monuments on the landscape of County Mayo.