Meán Scoil Mhuire was founded by the Sisters of Mercy who came to Longford from Mother House in Baggot Street, Dublin in April 1861.
They first lived in Keon's Terrace and taught young children in the ground floor room of the old St. Micheal's Boys’ School.
On Easter Sunday 1880, Bishop Woodlock laid the foundation stone of the primary school which opened to pupils in 1886.
This consisted of three classrooms, separated by folding doors which doubled as a study hall in evenings, plus a science room and cookery kitchen.
[citation needed] The subjects offered on the Senior Cycle (4th - 5th year) include: Accounting, Art, Biology, Business Studies, Career Guidance, Chemistry, Computers, English, French, Geography, History, Home Economics, Agricultural Science, Irish, Mathematics, Politics & Society, Music, Physical Education, Physics, Religious Education, and Spanish.