Unstrumental is Calabasas High School's award winning contemporary a cappella ensemble, led by CHS Vocal Music Director, Michael Siegel, and Voice and Performance Coach, Alana Weiss. It was founded in 2001 by former CHS Music Director, Joshua Barroll, and was directed by Barroll and Alana through the 21/22 school year.

Unstrumental is known for their powerhouse vocals, showstopping soloists, and dynamic stage performances and serves as a breeding ground for students wishing to pursue the performing arts in college or professionally. The CHS A Cappella program boasts many alumni who have gone on to study and perform music at prestigious universities and in the top a cappella groups in the country, as well as singers who have created successful contemporary music careers, and can be found performing on Broadway and in film and television.

Among the group's accomplishments include being two time featured performers at Carnegie Hall and three-time first place champions of the Los Angeles A Cappella Festival, where they have competed almost exclusively against collegiate groups, received numerous awards for their outstanding staging , and won the award for Best Soloist every time they have entered the competition.