The Brotherhood were invited by Archbishop Michael Kieran of Armagh to form a school because, "they gave the best education that has been offered to the youth of Ireland".
[3] The founder of the school was Brother Louis Yorke, an Englishman born in Manchester into a Protestant family.
A recent addition was a Technological Wing built with financial contribution from Senator Edward Haughey, a past pupil.
One of the four streams offer subjects through the medium of Irish Gaelic up to Junior Certificate Level but then students have to study through the English language only.
On 1 August 1990, the Christian Brothers left Dundalk after 121 years and handed over the school to the Armagh Diocese, with Cardinal Tomás Ó Fiaich as the chief trustee and patron.
Before the Brothers left Dundalk, they were honoured in the annual Saint Patrick's Day parade for their contribution to the town.
Many of the school's activities for students and staff are outside normal operating hours, including debating, sports, and science.
[10] Seán Ó Coigligh, an Irish teacher in Coláiste Rís, has helped prepare the teams every year.
[citation needed][vague] In science, students from Colaiste Rís have collected a number of awards from the annual Young Scientist Competition, including awards from the Geological Survey of Ireland, the Institute of Physics, the Irish Association of Speech Therapists, and others.