The Cathedral Girls' Choir, founded in 1945, sings at the 9 a.m. service each Sunday. The choir has appeared in concert with the Indianapolis Symphony Orchestra and has also performed on overseas tours, most recently in the summer of 2001. In addition to Westminster Abbey and St. Paul's Cathedral in London, the Girls' Choir has sung at the cathedrals of Lincoln and Canterbury, as well as in Scotland (St. Mary's, Edinburgh) and France (Notre Dame, Paris).

Choir members range in age from 8 to 18, the older girls providing both musical inspiration and acting as mentors for the younger girls. Membership is open to anyone; no musical experience is required, only an interest in singing and the ability to match pitch. The choir practices weekly from September through May. Children of all faiths are welcome.