The Castleknock College Union (referred to as ‘the Union’) is an association of pastmen, their parents, staff members of St. Vincent’s Castleknock College and the Vincentian Community associated thereto.
It has the distinction of being the oldest College Union in Ireland. The stated aim on formation in 1896 was to bring together the alumni, to keep them in touch with one another, so that old time memories and associations might be kept alive to play a part in working out the destiny of each.