The St. Sebastian's squash program began as a club sport in 2001 and has evolved into a varsity sport serving players at multiple levels. With the opening of the Burke Family Center in 2019, St. Sebastian's now hosts six state-of-the-art courts as part of the new squash complex. Players at both the high school and middle school level compete against other programs in the Independent School League and at the NEPSAC level. The varsity team also competes in regional and national squash tournaments.