"California Dreamin'" is a song written by John Phillips and Michelle Phillips and was first recorded by Barry McGuire. However, the best known version is by The Mamas & the Papas, who sang backup on the original version and released as a single in 1965. The song is #89 in Rolling Stone's list of the 500 Greatest Songs of All Time. The lyrics of the song express the narrator's longing for the warmth of Los Angeles during a cold winter in New York City.

The song became a signpost of the California Myth and the arrival of the nascent counterculture era.

"California Dreamin' " was certified as a Gold Record (single) by the RIAA in June 1966 and was inducted into the Grammy Hall of Fame in 2001.

The song was written in 1963 while John Phillips and Michelle Phillips were living in New York. He dreamed about the song and woke her up to help him write it. At the time, John and Michelle Phillips were members of the folk group "The New Journeymen", which evolved into The Mamas & the Papas. Also Nancy Sinatra recorded a cover version.

They earned their first record contract after being introduced to Lou Adler, the head of Dunhill Records, by Barry McGuire. In thanks to Adler, they sang the backing vocals to "California Dreamin'" with members of the session band The Wrecking Crew on McGuire's album This Precious Time. The Mamas & the Papas then recorded their own version using the same instrumental and backing vocal tracks to which they added new vocals and an alto flute solo by Bud Shank. P. F. Sloan did the guitar introduction. McGuire's original vocal can be briefly heard on the left channel at the beginning of the record, having not been completely wiped.

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