"Last Night When We Were Young" is a ballad composed by Harold Arlen with lyrics by E.Y. "Yip" Harburg, written in 1935. The song stands apart from much of Arlen's output for its austere emotional complexity and harmonic sophistication. Both Jerome Kern and George Gershwin reportedly cautioned Arlen that the music was too esoteric for popular consumption, and Johnny Mercer declined to write lyrics for it, finding the material too challenging. Harburg ultimately took on the task, drawing from a deeply personal period in his life marked by the loss of his first marriage, his father's death, and a business failure. The resulting lyric, described as unique in Harburg's catalog, captures the irrevocable loss of love with an unflinching directness that matched Arlen's introspective melody. The song initially met commercial resistance, with studios rejecting attempts by Lawrence Tibbett, Judy Garland, and Frank Sinatra to feature it in films. Over time, however, the composition found its audience among discerning musicians and listeners who recognized its artistic depth. Sinatra's 1954 recording, arranged by Nelson Riddle and included on the landmark album In the Wee Small Hours, became the most celebrated interpretation and helped elevate the song to its place in the American songbook. The composition represents an important example of a jazz-era popular song that prioritized emotional authenticity and musical invention over commercial accessibility.