Choir III is the main performing ensemble of the award-winning Bach Children's Chorus. Choir III Cantabile members sing repertoire both with Choir II as mentors, and with Choir III Chamber members as mentees. Participants are expected to have a strong musical background through the BCC (or a comparable choir) program and will sing a wide variety (and a large quantity!) of choral music including a capella and accompanied pieces in three or more parts.

Team-building retreat days and participation in local events are also a key feature of this program. Participation in the sight-singing program is mandatory and built into the rehearsals. Weekly music homework assignments help each singer build skills and confidence and are mandatory for all choristers to accomplish. Choir III emphasizes performance excellence through choral music.