According to Tom DeLonge in the liner notes of the album, the song came from a picture he had in his head about a girl and a boy in a car with it raining outside (hence the 'Down, Down, Down, Down' chorus) and how much the boy wants to kiss her and make her stay (another reason many suspect for the chorus). It has also been said that this was an "ode" to Mark's ex-girlfriend, before he met his wife.
An alternate arrangement of the song is available on the "Part 2" single, called the "T.L.A. Arrangement", which was done by the song's mixer Tom Lord-Alge. It is slightly different, featuring an extended ending where Hoppus's vocals are sung over the main chorus instrumental. Also the main guitar riff is panned completely to the left as opposed to it having a small presence at the right on the main version.
- At their August 29, 2009 show in Hartford, Blink played this song after their tribute to DJ AM.
- "Down" has been played live by DeLonge's band Angels & Airwaves as an intro to their first single "The Adventure".
The music video features aerial footage of Los Angeles and the band attending a backyard party. A police officer, played by actor Terry Crews, enters the party in search of a gang member, who escapes, and whom the officer pursues. At one point in the video, Crews clearly mouths the word fuck as the gang member escapes over the wall.
Travis Barker recorded the video with a broken foot.