"Night and Day" is a popular song by Cole Porter that was written for the 1932 musical Gay Divorce. It is perhaps Porter's most popular contribution to the Great American Songbook and has been recorded by dozens of musicians.

Fred Astaire introduced "Night and Day" on stage. His recording of the song with the Leo Reisman orchestra was a No. 1 hit, topping the charts of the day for ten weeks. He performed it again in the 1934 film version of the show, renamed The Gay Divorcee, and it became one of his signature songs.

Frank Sinatra recorded the song at least five times, including with Axel Stordahl in his first solo session in 1942 and again with him in 1947, with Nelson Riddle in 1956 for A Swingin' Affair!, with Don Costa in 1961 for Sinatra and Strings, and a disco version with Joe Beck in 1977. When Harry James heard Sinatra sing this song, he signed him. Sinatra's 1942 version reaching the No. 16 spot in the U.S.