St Mary's Cathedral College (SMCC) is a private, Roman Catholic secondary day school for boys, located in the Central Business District of Sydney, New South Wales, Australia. Founded in 1824, it is the oldest Catholic school in Australia and among the oldest schools in the country, currently catering for approximately 750 students from Years 5 to 12. It is owned by the Archbishop of Sydney and operates as a systemic school. It is attached to St Mary's Cathedral.