The school has existed in various forms for over 400 years, its constitutions reflecting the changing outlook and needs for society.

In 1907, the school buildings were conveyed to the Incorporated Society who closed their boarding school at Primrose Grange under Knocknarea and built dormitories and classrooms (the present boy’s dormitories and "Prep Room") on the present site, of Sligo Grammar School.

"The Hermitage" was destroyed by fire in November 1976 and was replaced by a new residence in September 1978.

[citation needed] An extension to the school, including more classrooms and a new library, was completed in September 2012.

[3][failed verification] The school also had a successful period, under the coaching of teacher Oliver Morris, in the 1999 and 2000 seasons.