KILLALA, DIOCESE of. - It comprises parts of the Irish counties of Mayo and Sligo.
Out of a population of 56,980 inhabitants, it has 55,246 Catholics (1936 census), distributed among 22 parishes, served by 55 diocesan priests; it has an ecclesiastical college (St. Muredach's College), 6 communities of religious women, 108 primary schools, 5 secondary schools, and 2 vocational schools. It is a suffragan of Tuam. The episcopal residence is at Ballina.
Its first bishop was St. Muredach, to whom St. Patrick entrusted, in the middle of the 5th century, the care of the church called Cell Alaid, from which the diocese derived the title Allodensis. The patron of the diocese is St. Muredach himself (feast on 12 Aug.). Almost nothing is known of the succession of bishops of K. until the end of the 12th century; in the Middle Ages the Franciscans had the celebrated convent of Moyne and later that of Rosserk, founded in 1460; the Dominicans had the abbey of Rathfran.