The school was founded by the Irish Christian Brothers in 1866. The original school was on Divis St in the lower Falls Road area of Belfast. In 1929, a new secondary school was built in the nearby Barrack Street. The students were largely drawn from the surrounding district but also began to attract some from across Belfast and wider afield. Due to the growing student population, it was decided in the 1960s to build a new school. This opened in a site off the Glen Road in 1968. The Barrack Street campus remained in use until 1998 when all students were accommodated in the greatly extended school on the Glen Road. The school was originally entirely run by the IrishChristian Brothers but in the late twentieth century their numbers declined and the school is now entirely staffed by lay teachers. It is now under the trusteeship of the Edmund Rice Schools Trust.
Academics
The school provides instruction in a broad range of academic subjects. At the advanced level students are prepared for exams in Applied Business, Business Communication Systems, Biology, Chemistry, Mathematics, Further Mathematics, Physics, ICT, Computing, Art & Design, Geography, History, Religious Studies, Politics, English Literature, Drama, Irish, Music, Sports Studies, Media Studies, Home Economics, French, SpanishTravel and Leisure. St Mary's also offer a double award science option and a further maths option which pupils are chosen for. in 2018, 81% of its entrants achieved five or more GCSEs at grades A* to C, including the core subjects English and Maths.. 74.4% of its students who sat the A-level exams in 2017/18 were awarded three A*-C grades.
Sport
Gaelic Games
The school hurling team won five Mageean Cup titles in succession in the 1990s and again three times since 2010. St. Marys also completed an Ulster Colleges double in 2008 winning both the Mageean Cup and the MacLarnon Cup for the first time in the school's history after beating St Columbs 1-7 to 0-8 in the final at Healy Park in Omagh on St Patrick's Day. The school has also had sustained success in handball and Gaelic football.
Soccer
Since the lifting of the ban on school representation in soccer competitions in 2002 the school has become the most successful in Belfast. On St Patrick's Day 2006 at Lisburn Distillery's grounds the Year 12s won its first ever soccer cup, the Belfast Cup, defeating Boys Model School. They followed up the next year with its first NI Cup in 2007 as well as the 2007 Belfast Cup. This success was followed up in 2008 as they won the year 9 Belfast Cup as well as an historic double in lifting both the Carnegie Schools Northern Ireland Cup and became the first school in 20 years to retain the Malcolm Brodie northern Ireland Trophy with a victory over St Columbs, Derry. The winning tradition continues into the last year of the decade with wins in the NI Cup and Belfast Cup for the U14s and the U15s winning the Belfast cup.
Water polo
It is the only school in Ireland to have a clean sweep of All-Ireland titles at all age groups in consecutive years. A 9th Canada Cup in a row was won in April 2009 with several of the team continuing to represent Ireland at international tournaments.
The school runs debating societies in English, Irish and Spanish, and has sent delegates representing Ireland to both the European Youth Parliament and European Youth Commission. The school has excelled in the European and Irish News inter-school quizzes, currently holding both trophies. The school debating team won the Northern Ireland Schools Debating Championship in 2008, defeating the team from Antrim Grammar School in the final at Stormont. This is the only time St Mary's has won the competition.
Arts
The school maintains an orchestra and a recording studio, stages theatrical and musical performances, as well as entering students in art competitions.
Notable alumni
See also: Past Pupils, St. Mary's CBGS, Edmund Rice Schools Trust
