A cappella music refers to vocal music performed without instrumental accompaniment. College a cappella generally covers groups that sprang from the tradition started by the Yale Whiffenpoofs in 1909. Groups typically have ten to twenty singers so that multiple voices cover each part, but are smaller than a typical chorus.

A cappella groups often sing in a horseshoe formation called the "shoe," but with occasional choreography the look can be varied. Often soloists may step out and stand in front to sing, accompanied by the rest of the shoe. Unlike a typical chorus, the musical conductor of an a cappella group, often referred to as the "pitch," does not stand in front of the center of the group with his or her back to the audience, but instead conducts while standing and singing in the shoe.

The styles of songs performed by a cappella groups can vary widely, from barbershop to jazz to contemporary rock to Christian to school songs. At Yale, 15 a cappella groups, including The Whiffenpoofs and Whim 'n Rhythm, are members of the Singing Group Council. There are several female, male, and co-ed groups, and each group has its own style and repertoire.