Crosby, Stills & Nash is a folk rock supergroup made up of David Crosby, Stephen Stills and Graham Nash, also known as Crosby, Stills, Nash & Young when joined by occasional fourth member Neil Young. They are noted for their intricate vocal harmonies, often tumultuous interpersonal relationships, political activism, and lasting influence on music and culture. All four members of CSNY have been inducted into the Rock and Roll Hall of Fame twice, though Young's multiple inductions were for work not involving the group.

Initially formed by the trio of David Crosby, Stephen Stills and Graham Nash, the genesis of the group lies in two 1960s rock bands, The Byrds and The Hollies, and the demise of a third, Buffalo Springfield. Friction existed between David Crosby and his bandmates in the Byrds, and he was dismissed from the Byrds in the autumn of 1967.

By early 1968, Buffalo Springfield had also disintegrated over personal issues, and after aiding in putting together the band?s final album, Stephen Stills found himself unemployed by the summer. He and Crosby began meeting informally and jamming, the results of one encounter in Florida on Crosby?s schooner being the song ?Wooden Ships,? composed in collaboration with another guest, Paul Kantner of Jefferson Airplane.

Graham Nash had been introduced to Crosby when the Byrds had toured the UK in 1966, and when the Hollies ventured to California in 1968, Nash resumed his acquaintance with Crosby. At a party in July 1968 at Cass Elliot's house, Nash asked Stills and Crosby to repeat their performance of a new song by Stills, ?You Don't Have To Cry,? with Nash improvising a second harmony part. The vocals gelled, and the three realized that they had a unique vocal chemistry.