Riordan is the only high school in San Francisco to have its own marching band. The program consists of marching, concert, jazz, and pep bands. At Riordan, the majority of musicians pick up their new instruments in their freshman year while enrolled in the Instrumental Music Ensemble (Beginning Band). They move into the Intermediate Band as sophomores and join the marching band in the second semester and their junior and senior years. The band program is one of the few high school music programs that starts students with no musical experience.