Chicago a cappella is a non-profit organization devoted to furthering the art of ensemble singing without any instruments. The group of professional singers began in 1993 by Jonathan Miller and conduct a series of performances annually. The organization displays a yearly subscription series for Chicago residents, produces studio recordings as well as live and broadcast-media musical content, and performs on tour and in special arrangements. The ensemble is known for their outstanding vocal abilities, innovative programming, and have a reputation of being a leader within the choral field. Expanding from a collection of a Gregorian chants to the Beatles and beyond, the singers are known for their wide repertoire including early works, vocal jazz, and spirituals. The ensemble is also a champion of performing works by living composers.