Mindless Behavior: 21 Under 21 (2012)

Mindless Behavior: 21 Under 21 (2012)

No. 13: Mindless Behavior

Last Year's Rank: 16

Birthdates: Prodigy - Dec. 26, 1996; Ray Ray - Jan. 6, 1997; Princeton - April 21, 1997; Roc Royal - July 23, 1997 (All age 15)

Why They're Hot: The R&B quartet has seen a success since stepping into the spotlight in2010. Their first studio album, "#1 Girl" (2011), debuted at No. 2 on the R&B/Hip-Hop Albums chart and delivering three chart-climbers including "My Girl," "Girls Talkin' Bout," and "Mrs. Right," featuring Diggy, which peaked at No. 8 on the R&B/Hip-Hop Songs chart. Since embarking on their U.S. #1 Girl Tour on July 5, Mindless Behavior has been working on their second studio album. As Interscope Record preps the album's first single, the guys point out that the key of their project is growth. "The second album is going show everyone that we're not kids anymore," Princeton tells Billboard. "We're teenagers. We're a boy band, but we're not kids."

Video Below: Mindless Behavior's "Hello"

Next: Cody Simpson