The OBA was formed by accident rather by design when the Rev J S Nagle, Principal of ACS (1913 – 1922) was tasked with fulfilling Bishop William F Oldham's vision of building an ACS College. The Rev Nagle contacted the Old Boys, some of whom were distinguished citizens holding prominent positions in society then, to garner their support to realize Bishop Oldham's dream. Though this dream failed to materialize, the ACSOBA was formed. It was officially formed on 10 July 1914, 28 years after ACS was started at Amoy Street.

Throughout the years, the OBA not only provides a venue for the Old Boys to network among themselves, they also made their presence felt throughout all ACS units via three distinct events that have since become firm traditions: The annual Founder's Day Dinner; fund-raising (e.g. the Fun-o-Rama); and "Past v Present" Games.

The Old Boys' collective loyalty, gratitude, generosity and passion, as seen in the OBA's involvement with the ACS units, are the driving forces of the association that keep it from fading into oblivion.

For more information / to join the ACSOBA, visit the official ACSOBA site.