Formed by Frank Zappa in 1964, The Mothers of Invention released their double-LP debut "Freak Out" in 1966. The faux-psychedelic sound on the album belied its satirical social commentary that would become the Mothers' trademark, while other influences from rhythm and blues to doo-wop played side by side with the more avante-garde compositions. Though Freak Out was initially hard for many US audiences to swallow, it quickly became popular in Europe, and influenced The Beatles' production of Sgt. Pepper's Lonely Hearts Club Band.
