Two schools existed in Castlegal in the 1870s. Castlegal Girls School had an enrolment of 132 in 1870 and an average attendance of 46. In 1902, the Girls school was replaced by a new school built on land donated by the late Lord Ashley of Classiebawn Castle. [He had replaced Lord Palmerston] It had one teacher and between 40 and 60 pupils. In 1931, pupils and staff changed places with Castlegal Boys School which was nearby [Magee’s Shop] and it became a two-teacher school.
In 1950, the Boys and Girls amalgamated onto the site where Scoil Naomh Mhuire is now situated. A second classroom was added on and the school became known as Scoil Naomh Mhuire. A number of improvements have been carried out over the years. Initially, a staff room/learning support was added to the school building. A set down area for cars and new parking facilities were developed in 2013/2014. In 2015, a major extension was undertaken. A spacious new classroom, an office and a medical room were added. The two older classrooms were opened into one bigger classroom.
Today Scoil Naomh Mhuire is a bright, spacious building which accommodates up to 50 pupils.
In 2017, there are two mainstream class teachers, a Special Education teacher, two Special Needs Assistants and a part-time secretary and caretaker. The school is supported by an active Parents Association. Scoil Naomh Mhuire is a happy , progressive school which is proud of its long history in education and seeks to continue this tradition into the future.