If you were looking for an indication of just how far Fall Out Boy’s star had risen since the release of 2005’s From Under the Cork Tree, consider this: the first voice you hear on the band’s third full-length is not that of vocalist/guitarist Patrick Stump, but stratospherically famous hip-hop impresario (and Island Def Jam president) JAY-Z. That the rapper comes from a world beyond emo/pop-punk sends a clear statement: the Chicago quartet was no longer content to simply conform to genre expectations and stay in their stylistic lane. And so it proves with Infinity On High, an album that embellishes the band’s anthemic, guitar-charged melange of emo, pop, hardcore, and punk rock with hints of soul (“I’m Like a Lawyer With the Way I’m Always Trying to Get You Off (Me & You)”) and stomping funk and ’90s R&B (“This Ain’t a Scene, It’s an Arms Race”). Swirling strings punctuate the orchestral pop-punk of “Thnks Fr Th Mmrs” and skittering programmed beats usher in “The (After) Life of the Party,” but perhaps the biggest stylistic leap comes in “Golden,” in which Stump croons over a somber piano accompaniment before layers of backing vocals build to an almost Beach Boys-like choral crescendo. The band also looked beyond genre boundaries for contributors, enlisting P!nk collaborator Butch Walker to contribute to several tracks and co-produce “Don’t You Know Who I Think I Am?” R&B legend Babyface, meanwhile, plays mandolin and organ on “I’m Like a Lawyer...” and “Thnks Fr Th Mmrs,” which he also produced. (Neal Avron, who helmed From Under the Cork Tree, handles the remainder of the LP.) Thematically, Infinity On High hues a little more faithfully to the band’s past, with bassist/lyricist Pete Wentz continuing his penchant for crafting lyrics equal parts self-absorbed, self-deprecating, overtly dramatic, and laced with black humor. Opener “Thriller” pits the band as underdogs, victims, and triumphant heroes all within the space of three-and-a-half minutes, covering the lukewarm critical reception to From Under the Cork Tree (“Last summer we took threes across the board”), the pace of their rise (“But by fall we were a cover story now in stores”), and the absurdity of fame and the increased scrutiny and attention (“Make us poster boys for your scene/But we are not making an acceptance speech”). “This Ain’t a Scene, It’s an Arms Race,” meanwhile, is a response to the mid-2000s emo-punk explosion, with Fall Out Boy joined at the top of the charts by acts such as My Chemical Romance, Paramore, and Panic! At the Disco. Infinity On High, however, proved they’d not be confined to being the kings of any one genre.