Infinity on High is the third studio album by American rock band Fall Out Boy, released on February 6, 2007, by Island Records. Recorded from July to October 2006 at Pass Studios in Los Angeles, California, its music was composed by lead singer and guitarist Patrick Stump and the lyrics were penned by bassist Pete Wentz. The album features collaborations with new producers and guest artists, such as Babyface and Jay-Z, and sees the band experimenting with genres including R&B, soul, and flamenco. Fall Out Boy also utilized instruments such as horns, violins, and pianos, which had not been used on previous releases.

As reported by Billboard, the band "[drifted] further from its pop punk roots to write increasingly accessible pop tunes", a slight departure from the group's previous sound. Critics felt that its lyrics served as a response to the band's rise to fame. Fall Out Boy embarked on several tours to promote the album, including the Friends or Enemies Tour, the Honda Civic Tour, and the Young Wild Things Tour.

Infinity on High debuted at number one on the US Billboard 200, selling over 260,000 copies in its first week of sales and becoming the band's first number-one album. It also reached number one in New Zealand and peaked within the top-five of countries including Canada, the United Kingdom, and Australia. Five songs were released as singles, four of which charted on the US Billboard Hot 100; the second single, "This Ain't a Scene, It's an Arms Race", peaked at number two. The album received generally positive reviews from critics, with many praising Stump's vocals and the band's new musical direction, and has sold over two million copies worldwide and over 1.4 million in the United States alone.