Bittersweet World is the third studio album by American recording artist Ashlee Simpson. It was first released in Australia on April 19, 2008, with a release in the United States following on April 22. The project serves as her third and final release through Geffen Records. Simpson first spoke of a third album following her run as Roxie Hart in the musical Chicago in 2006. Work on the project officially began in 2007, with Geffen announcing an October release date. The album was initially titled Color Outside the Lines, taken from a line in the song "Rule Breaker". Simpson claimed in November 2007 that she had finished the album, though she continued to write new material.
Simpson took more creative control over the project, co-writing all eleven songs on the standard edition of the album. Hoping to create a "fun party album", Simpson enlisted producers Timbaland and Chad Hugo and Kenna of The Neptunes among others to create a more "beat-oriented" sound that differed from her previous pop-rock releases. The album incorporates elements of pop and dance-pop music, and was influenced by the pop-music scene of the 1980s. Bittersweet World lyrically speaks of relationships and life in the public eye, among other topics. The album was released to a generally positive reception from music critics, many of whom praised her musical transition to a more pop driven sound.
The album debuted at number 4 on the Billboard 200 chart in the United States, with estimated first week sales of 47,000 copies. It became her first album to not reach the top of the chart, as well as her lowest first week sales thus far. The album went on to sell 126,000 copies by 2009, her least successful effort to date. The album's lead single, "Outta My Head (Ay Ya Ya)", became her first to not appear on the Billboard Hot 100 chart in the United States, though it was a moderate success in other territories. Shortly following the release of "Little Miss Obsessive" as the second single, Simpson announced her pregnancy, thus promotion for the album concluded. Simpson embarked on a thirteen date club tour to promote "Outta My Head (Ay Ya Ya)", where she performed songs from the album. The album was further promoted through various televised performances and interviews.