Crosby, Stills & Nash was a folk rock supergroup made up of American singer-songwriters David Crosby, Stephen Stills, and English singer-songwriter Graham Nash. When joined by Canadian singer-songwriter Neil Young as a fourth member, they were called Crosby, Stills, Nash & Young. They are noted for their intricate vocal harmonies and lasting influence on American music and culture, as well as their political activism and often tumultuous interpersonal relationships.