Thirteenth Step is the second studio album by the American rock band A Perfect Circle. The album was released as a compact disc on September 16, 2003. The album was a success, reaching the #2 position on the Billboard charts in its premiere week, selling over 231,000 copies. The RIAA certified it as gold on November 4, 2003 and as platinum on March 24, 2006.

The first single from the album was "weak and powerless", followed by "The Outsider" and "Blue". The tracks have their remixed versions on a 2004 remix album aMotion. It has been speculated that the title is a reference to the Twelve-step program. According to Keenan on the commentary for the aMotion DVD, the album is a concept album with all of the songs dealing with the problem of addiction from a different perspective. He said that it refers in a way to his 13 years of residence in Los Angeles. "The Nurse Who Loved Me" is a cover of the song by Failure, originally featured on the 1996 album Fantastic Planet. "Pet" has its follow-up, "Counting Bodies Like Sheep to the Rhythm of the War Drums", with the same lyrics, on the band's following 2004 cover versions album Emotive. User-contributed text is available under the Creative Commons By-SA License and may also be available under the GNU FDL...