House System
There are four Colour Houses within the school, which compete against each other in the College Carnivals. Every student is placed in a House when she enters in Year 7 and she stays in that House until she leaves the school. Each Colour House name has a special significance in the heritage of the College.
- Stanley: "The crown to the one who tries"
- This colour house was named after Sr. M. Alphonsus Stanley and Sr. M. Gonzaga Stanley who were sisters, Sisters of Mercy and principals of OLMC from 1946 and 1964.
- Clare: "Be Faithful"
- Clare is named after Mother Mary Clare Dunphy who was the leader of the group of Sisters who came from Callan, Ireland, in 1888 to establish OLMC.
- McAuley: "Not for us but for all"
- McAuley is named after Catherine McAuley, founder the Sisters of Mercy in Dublin, Ireland, in 1831.
- Mercedes: "In this sign we will achieve"
- The word "Mercedes" is Spanish for mercy. As this concept is a vital part of OLMC's heritage and identity, it is appropriate that a colour house be named after it.
College Carnivals
Students are encouraged to demonstrate their House spirit by participating in the three major school sporting carnivals throughout the year. These are the Annual Swimming Carnival, Cross Country Carnival and the Athletics Carnival.