St Mary's enjoys an outstanding reputation for music and is blessed with excellent facilities in a purpose-built four-storey music school. A delightful recital room with panoramic views and rewarding acoustics sits above 15 dedicated practice rooms all with modern pianos, and a ‘state of the art’ studio is equipped with the latest technology for recording and composition. The Chapel, at the heart of the school, is the main concert venue, and with each boarding house having a piano, music is heard in both formal and informal settings throughout the day.

The Fourth Form curriculum includes music as an academic subject each week; older girls choose it as an option. Academic results are outstanding at GCSE, AS level and A2 level, the small class sizes (typically 7 at GCSE and 3 at A level) allowing individuals to flourish. Girls regularly go on to read Music at the leading universities, and four former Calne girls presently hold Choral Scholarships at Oxford.