The record features outer space-inspired production sounds, with OutKast and producers Organized Noize incorporating elements of dub, psychedelic rock, and gospel into the compositions. Several songs feature the duo's first attempts at producing music by themselves. Lyrically, the group discusses a wide range of topics including urban life as hustlers, existential introspection, and extraterrestrial life. The album's title is a portmanteau of "ATL" (an abbreviation of Atlanta, Georgia) and "aliens", which has been interpreted by critics as a commentary about the feeling of being isolated from American culture.

Tracklist

A1 You May Die (Intro) 1:05
A2 Two Dope Boyz (In A Cadillac) 2:46
A3 ATLiens 3:50
A4 Wheelz Of Steel 4:03
B1 Jazzy Belle 4:12
B2 Elevators (Me & You) 4:25
B3 Ova Da Wudz 3:48
C1 Babylon 4:24
C2 Wailin 2:00
C3 Mainstream 5:18
D1 Decatur Psalm 3:58
D2 Millenium 3:09
D3 E.T. (Extraterrestrial) 3:07
D4 13th Floor / Growing Old 7:50
D5 Elevators (ONP 86 Mix) 4:35