"Don't Know Why" is a song written by Jesse Harris that originally appeared on his 1999 album, Jesse Harris & the Ferdinandos. It was the second single by American singer Norah Jones from her debut studio album Come Away with Me (2002). Jones's version peaked at No. 30 on the U.S. Billboard Hot 100 and was a critical success, helping establish her as a respected new artist, and subsequently her album sold extremely well. The single went on to win three Grammy Awards in 2003 for Record of the Year, Song of the Year, and Best Female Pop Vocal Performance. It remains Jones's biggest hit single in the United States to date, and her only one to reach the top 40 of the Billboard Hot 100. The single was also a hit internationally and reached top 10 in several countries. The song charted at 459 in Blender magazine's 500 Greatest Songs Since You Were Born.
A music video directed by Anastasia Simone and Ian Spencer was released in 2002.