St Mary's College (formerly Christian Brothers College, St Kilda, Presentation College, Windsor) is an independent Catholic co-educational secondary college, located in Melbourne, Victoria, Australia. The school was founded in 1878 and is both one of the oldest private schools in Melbourne and one of the only co-educational Catholic schools in inner Melbourne.

Originally founded as Christian Brothers College, St Kilda (CBC St Kilda), and run by the Christian Brothers, the school has long since had a lay teaching and administrative staff; becoming co-educational as St Mary's College in 2021 following the closure of Presentation College Windsor (PCW).

The college is governed by Edmund Rice Education Australia and is also members of Associated Catholic Colleges and Catholic Girls Sports Association of Victoria.