"Don't Know Why" is a song written by Jesse Harris in 1999 in New York City. Harris, a guitarist and singer-songwriter known for blending folk, pop, and jazz sensibilities, recorded the tune shortly after composing it for his album with the Ferdinandos, where it appeared in a spare, acoustic arrangement with violins. The song's gentle, introspective quality is built on a descending melody that conveys longing and regret, supported by sophisticated harmony featuring circle-of-fifths motion and secondary dominants that lend a subtle jazz inflection to its folk-pop framework. Harris has noted that despite the song's themes of loss and isolation, it is not autobiographical. The composition gained worldwide recognition through Norah Jones's recording on her 2002 debut album Come Away with Me, released on Blue Note Records. Jones had met Harris in 1998 at a University of North Texas clinic, and he encouraged her move to New York, where her first-take demo of the song became the definitive version. Her recording, recast with piano, upright bass, and brushed drums, peaked at number 30 on the Billboard Hot 100 and won three Grammy Awards, including Record of the Year and Song of the Year. The tune's concise form and harmonic elegance have made it a widely covered modern standard, interpreted across genres from intimate acoustic settings to full jazz ensemble arrangements.