Outsider music is music performed either by social outsiders, who have no or few associates in the mainstream music business, or by musicians who choose to live and work apart from the music industry, often due to compromising behavioral or psychological conditions. Outside music reflects these conditions in various ways. Lyrics are often bizarre or emotionally stark and songs show a great disregard for structural conventions or popular trends in mainstream music. Also, outsider musicians frequently have no formal training and/or significant music skills in the traditional sense. The end result is music that is much stranger and more abrasive than more popular musical styles. Outsider music is a form of outsider art.

The main article for this category is Outsider music.