The school is divided into four “house” groups or Clanns. Each Clann has a distinctive name, a tradition, an emblem and a colour. The Clanns are named after four ancient Irish northern kingdoms: Oriel, Aileach, Uladh and Midhe.
Students are assigned to a house on arrival in the school and remain with that house over their six years. Each Clann has three leaders, ideally one from 6th year and one from 5th and one from 4th (designated Taoiseach, Tanaiste, Runai) who form a Council for each clann. The 6th year leaders are, in effect, the school captains.
The mainstay of the Clann system is a series of competitions or (sporting and academic) held usually at the end of each term (feis days) between the houses. The school sports day is also a clann event (ard fheis).
Extra-curricular activities, especially in representing the school, competitions, team or individual sports and personal achievement areas (music, public speaking), will be rewarded with clann points.
Jobs undertaken in the school also allow Clanns to score points over the course of the year. The School Awards include an overall Clann trophy which the Clanns will seek to defend from year to year, and may also include a Clann member-of-the-year award. In May 2015 Midhe won the Clann of the Year trophy for the third consecutive year.