Lovato, 5, the daughter of Dianna De La Garza – a former Dallas Cowboys cheerleader and country music singer ("I got my voice from her," Lovato says) – attends a local casting call for Barney & Friends. Because she can't read yet, Lovato doesn't land a role on the show until she's 6. She spends two seasons on Barney alongside best friend and future Disney star Selena Gomez.
Post-Barney, Lovato moves from entertaining the toddler set to entertaining the tween set when she's cast on As the Bell Rings, a series of comedic shorts that run between Disney programs. "Even though the show was only, like, five minutes, it was the Disney Channel!" Lovato tells Entertainment Weekly in 2008. "I thought it was the coolest thing."
The Jonas Brothers' Disney Channel movie Camp Rock premieres with 8.9 million viewers, making it the most-watched cable program of the year. In the TV movie, Kevin, 20, Joe, 18, and Nick, 15, star as pop stars sent to a rock camp, where Joe flips over Lovato's poor-girl-with-a-booming-voice character. "Joe is a big dork," Lovato tells PEOPLE. "Nick is witty and sarcastic – sometimes I think he's the funniest. Kevin plays the older-brother role. They're all really, really great."
With Gomez, now the star of Wizards of Waverly Place, Lovato shoots the Disney Channel movie Princess Protection Program. In the original TV flick, Lovato plays a princess-in-hiding who covers as an ordinary teen with the help of Gomez's character. Lovato also begins shooting her forthcoming Disney TV series Sonny with a Chance.
Lovato drops her debut album Don't Forget, a pop-rock collection that contains songs featuring and co-written by the Jonas Brothers. "Kelly Clarkson, when she first went rock, was totally my inspiration," Lovato tells EW. "I realize, though, that I'm a pop singer. And I'm not gonna try to be too 'Oh, I'm hardcore, I'm a rock girl.'" In its first week, the album is the top seller on iTunes.
Lovato becomes the Disney Channel's newest leading lady on Sonny with a Chance. The singer plays Allison "Sonny" Munroe, star of the fictional sketch-comedy show So Random!. "In the beginning I was so stressed out," she tells the New York Daily News of fronting the show. "There's a lot of pressure to carry a show when you're my age. [But] I could not be more excited with it."
With the upcoming premiere of their movie, Princess Protection Program, Lovato and BFF Selena Gomez appear in a special edition of PEOPLE. In the issue, Lovato opens up about finding and maintaining strong friendships. "I've cut out the people who I don't need in my life," she tells PEOPLE. "I realized I should surround myself with people who make me smile."
After months of speculation linking Lovato to longtime pal Joe Jonas, Lovato finally spills the beans about her romance. "He's perfect," Lovato gushes to Access Hollywood's Billy Bush about her Camp Rock 2 costar. But in May, Joe breaks up with Lovato, whom he says he still loves as a friend.
After having a fight with a dancer on the road, Lovato, 18, drops out of her tour with the Jonas Brothers to check into a treatment center, where she's diagnosed with bipolar disorder. A source close to Lovato's family adds, "She fought through eating disorders and has struggled with cutting. [She] is taking control by getting help." Lovato, who experienced a "nervous breakdown," finishes treatment in January, and thanks her fans for helping her through "the darkest point in her life"
Nearly eight months after leaving treatment, Lovato releases her third album, Unbroken, which debuts at No. 4 on the Billboard albums charts thanks to the success of her lead single "Skyscraper." "I took a long time on this album, and I've been on such a journey over the past year that it just feels awesome to be able to release music that I've worked really hard on," she says, "and now that it's done well [on the chart] it feels even better."
BIOGRAPHY (top to bottom): Everett Collection; Disney; Kevin Mazur/Wiriemage; amazon.com; Disney; Splash News Online; INF; amazon.com