One Thing is a song by English-Irish boy band One Direction from their debut studio album, Up All Night. It was released in various countries by Syco Music on 6 January 2012, as their second single, and as their third single in the UK on 13 February 2012. Additionally, Columbia Records sent it to contemporary hit radio playlists on 22 May 2012 as their second single in the United States.
After being formed and finishing third in the seventh series of The X Factor in 2010, One Direction were signed to Syco Music. Recording for their debut studio album, Up All Night, began in January 2011. In February 2011, the boy band and other contestants from the series participated in the X Factor Live Tour. After the tour concluded in April 2011, the group continued working on their debut album. Carl Falk and Rami Yacoub produced three songs on the album: "What Makes You Beautiful," "One Thing" and "I Wish," all of which were co-written by Falk, Yacoub and Savan Kotecha. Initially, "One Thing" was written as two different songs: "One had a really, really good verse" and the other track "had a really, really good chorus", as noted by Falk in a 2012 interview with Examiner.com. Falk quipped that when they merged the two songs, "everything fell into place". Additionally, Falk deemed it the perfect accompaniment to "What Makes You Beautiful" and selected it as his favourite "out of the three tracks [that I have on the Up All Night album]".
Due to its resemblance to the aforementioned Backstreet Boys number, PopMatters's Zachary Houle suggested that there could occur "a pretty compelling case to launch a plagiarism lawsuit", concluding: "Homage or theft? You decide". Brian Mansfield from USA Today felt the song's Backstreet Boys-references "may or may not be intentional," but noted that the attribute "is the same." Lewis Corner from Digital Spy awarded the song four out five stars, complimented the song's guitar riff, its "forceful" chorus, and the melody as memorable, and summarised it as an "arena-ready hit".A Newsround reviewer gave the song four and half stars out five stars, praising the group's vocal performance and its sonic palette. Billboard correspondent Jason Lipshutz hailed "One Thing" as "perfectly executed pop rock" and opined that it "could own radio for months". Cosmopolitan's Sophie Goddard lauded "One Thing" as an "upbeat, catchy, hit-in-waiting," and Entertainment Weekly writer Adam Markovitz commended it as "irresistibly bouncy".