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Then: In January 2006, 13-year-old Cyrus was the squeaky-clean star of the Disney Channel's Hannah Montana. The show proved a launching pad for the actress, who later scored music and movie deals.
Now: Seven years later, on the verge of turning 21, Cyrus has shed her good-girl image by regularly stepping out in revealing clothing, chopping her long locks into an edgy pixie and releasing music that alludes to her party-girl ways. She's also got a new leading man in her life: fiancé Liam Hemsworth.
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Then: Fresh-faced, 14-year-old Gomez looked the part of her Disney Channel alter ego, Wizards of Waverly Place's Alex, when she attended the 2007 Pirates of the Caribbean: At World's End premiere.
Now: With a sultry new look and a rocky on-off relationship with fellow teen star Justin Bieber, the budding bombshell has embraced adulthood head-on, starring in the racy beach romp Spring Breakers and hitting the ESPY Awards red carpet in a leg-baring mini just days before her 21st birthday.
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Then: Say hello to Sharkboy! When he hit the red carpet for Son of the Mask in 2005, 13-year-old Lautner was best known as the superhero star of The Adventures of Sharkboy and Lavagirl 3-D.
Now: In 2013, Lautner became a grown-up – literally! – with his role in Grown Ups 2. The part marked a new chapter in his career following the end of The Twilight Saga, which skyrocketed the 21-year-old to fame – and sex-symbol status.
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Then: Like Cyrus and Gomez, 16-year-old Lovato first struck a chord with fans thanks to her girl-next-door demeanor and singing chops, assets that made her the lovable leading lady of the 2008 Disney Channel movie Camp Rock.
Now: Though her sudden success led Lovato to briefly check into a treatment center in 2010, the star, now 20, bounced back better than ever, releasing her third album in early 2011 and joining The X Factor in 2012, where she continues to serve as a judge.
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Then: The oldest of the Jonas Brothers, 18-year-old Kevin joined Nick and Joe in celebrating the August 2006 release of their debut album, It's About Time. Sales proved disappointing, but the trio soon hit it big after a 2007 Hannah Montana guest stint and later, their own Disney Channel movie, Camp Rock.
Now: No more purity ring! Kevin, now 25, traded the group's most famous accessory for a wedding band in 2009 when he wed longtime girlfriend Danielle Deleasa. The two are expecting their first child and have another season of their E! reality show, Married to Jonas, on the way.
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Then: Bieber's ascent to superstardom proved swift after Usher signed the YouTube sensation to his record label in 2007 and his best-selling 2009 debut album, My World, scored the 15-year-old an invite to that year's MTV VMA Awards.
Now: The 19-year-old has experienced some growing pains: After receiving rave reviews for his third album, he embarked on a world tour in 2013 that's seen its fair share of problems – and he's endured an on-again, off-again relationship with Selena Gomez.
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Then: Country music found its new queen in 2006 when 16-year-old Swift, all blonde curls and Southern charm, released her self-titled debut album and scored a loyal fan following thanks to her confessional lyrics and preference for PG-rated fun.
Now: Gone are the soft curls, but Swift's sugary-sweet persona remains unchanged in 2013, despite the 23-year-old's increasingly sexier red carpet style – seen here at the MuchMusic Video Awards on June 16 – and on-display dating life.
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Then: A former star of Nickelodeon's sketch comedy All That, Cannon, 20, was a household name when he attended the 2001 Teen Choice Awards, and he would later headline his own show for the network.
Now: What a difference a decade makes! Cannon has worked his way up from talent to big shot, being appointed chairman of TeenNick in 2009. In addition, the 32-year-old hosts America's Got Talent, runs production company N'Credible Entertainment and answers to "Dad," having welcomed twins Monroe and Moroccan with wife Mariah Carey in 2011.
9 of 10
Then: Twelve-year-old Stewart couldn't help but smile when she first earned attention as Jodie Foster's daughter in 2002's Panic Room.
Now: It's hard to picture The Twilight Saga star ever smiling so big now: Following her success as the franchise's heroine, Stewart, 23, has become notorious for her red carpet risks and less-than-comfortable relationship with the Hollywood limelight, particularly when it comes to her complicated love affair with costar Robert Pattinson.
10 of 10
Then: Promoting Harry Potter and the Sorcerer's Stone in 2001, the 11-year-old cast a spell on moviegoers and captured the world's hearts as mini Muggle Hermione Granger.
Now: As Harry Potter wrapped its epic reign, Watson stepped away from Hollywood in 2009 to attend Brown University, and later, Oxford. By 2012, the actress, now 23, was back in action, earning praise for her turns in The Perks of Being a Wallflower and 2013's The Bling Ring – as well as her sharp sense of style.