Composition and lyrics
"Round & Round" is a dance-pop song with a length of three minutes and eight seconds, composed by Kevin Rudolf, Andrew Bolooki, and Jeff Halavacs, Jacob Kasher and Fefe Dobson. The song is also disco-influenced electropop, with an uptempo dance vibe, featuring a light rock edge during the verses. Mikael Wood of Billboard said the song "rides a fist-pumping electro groove." According to Amar Toor of AOL Radio Blog, the song pulls influence from Kylie Minogue circa 2001. The song's lyrics speak of a relationship going around in circles. The song's middle eight is a sing-speak breakdown, in which Gomez raps her lyrics in a Ke$ha-esque fashion.
Bill Lamb of About.com praised Gomez's vocal maturity and rock edge likely thanks to producer Kevin Rudolf, calling the song "effortless" and would "sound good after months of airplay." Lamb commented the song was "catchy" and "will catch adult listeners right away", even though it was not deep and "pure fluff." Lamb also predicted with Miley Cyrus, "exploring adulthood around the corner, and threatening to leave pop music entirely, Selena Gomez is set to take the female teen pop crown in crowd pleasing fashion." Tim Sendra of Allmusic said that the song was "well sung" and noted it as one of the top tracks on the album. Becky Bain of Idolator said the song had an "infectious tune", and said "might actually be the song to get the non-Disney-centric demographic interested in Selena’s tunes." Although commenting that the "glossy electro-pop rock" of the song showed a sophisticated side of Gomez, and the lyrics showed emotional growth, Robert Cospey of Digital Spy said the good work was squandered by the "rusty" chorus. Overall, Copsey complimented Gomez for "avoiding the predictable Hilary/Miley teen-rawk route" and recommended she stay under the Disney umbrella to "perfect her craft further."
Propelled by a debut at number fifteen on the US Hot Digital Songs chart, "Round & Round" debuted at number twenty-four on the Billboard Hot 100, becoming the band's second consecutive top thirty single in the United States. It also appeared on the Billboard charts the Hot Dance Club Play and Pop Songs charts at two and thirty-four. However, it did not match the peaks of its predecessor "Naturally" on those charts, where the latter peaked at one and twelve. The song performed moderately in international markets. It reached fifty-one on the Canadian Hot 100. In the United Kingdom, it reached forty-seven, and was on the chart for three consecutive weeks. "Round & Round" charted in the top sixty in Austria, and Germany, and appeared on the Belgian Flanders tip chart, as well as charting in Slovakia.
The filming of the video was made by Phillip Andelman, and took place in late May 2010 in Budapest, Hungary during the filming of her film, Monte Carlo. Gomez posted two previews of the song on her Twitter on June 17, 2010 to precede the video's premiere on June 20, 2010 on Disney Channel and subsequently VEVO. Along with singing on a stage with the Scene, the video features Gomez acting as a secret agent and donning spy apparel, as she plants bugs, takes photos, passes off packages, and other duties. She is then caught and involved in a chase throughout the city. Nadine Cheung of AOL JSYK said, "We love the storyline for the video and how it's mixed in with performance shots of Selena and her band the Scene. Of course, the 17-year-old star is decked out in amazing outfits, no matter if she's rocking out on stage or being followed by cloaked agents."
- The song was performed by the band on America's Got Talent on July 14, 2010.
- From August 14, 2010, the song was performed on the Selena Gomez & the Scene: Live in Concert tour.
- It was also performed on Good Morning America on September 23, 2010 along with "A Year Without Rain".
- While promoting in the United Kingdom, Gomez appeared on Daybreak on September 27, 2010.
- The band performed the song on Blue Peter on September 28, 2010.
- Gomez performed the song on MTV's The Seven on October 1, 2010.
- Beginning October 20, 2010, Selena Gomez & the Scene performed the song on the A Year Without Rain Tour.
- Beginning July 24, 2011, Selena Gomez & the Scene performed the song on the We Own the Night Tour.
- On January 19, 2013, Gomez performed the song at the UNICEF Charity Concert.
- Beginning August 14, 2013, Gomez performed the song on the Stars Dance Tour.