Their third album, From Under the Cork Tree, was released in 2005.Wentz wrote the lyrics to the lead single, "Sugar, We're Goin Down" with his dad in Chicago; the song peaked at #8 on the Billboard Hot 100 and spent months in the top 50 of the Hot 100, marking five weeks in the top 10 and fourteen weeks in the top 20.On January 12, 2012, the band announced via Facebook that vocalist Bebe Rexha was no longer a member of the group.
In 2002, Fall Out Boy released an EP called Fall Out Boy/Project Rocket Split EP.
He and Arma Angelus' bassist Joe Trohman founded the pop-punk band Fall Out Boy after Trohman introduced Pete to a musical acquaintance, Patrick Stump.
Andy Hurley agreed to drum part-time, but only joined the band full-time later.
Originally, the band had planned to release a full-length LP in the summer of 2011.
However, after several delays, the departures of both Patterson and Rexha, and general uncertainty about the band's future, the group reshuffled, scrapping the original album and announcing plans to release a mixtape, write new material, and continue to remix tracks by other artists.