"I wanted to do something you could hear in a club or something you could dance to, something that's fun—something that's me. I think it was definitely because I was getting older. But it was also a kind of a scary thought. 'Cause you go, 'I don't want to offend my brothers.' You know?"

But when he approached Nick and Kevin, they were all for it. He also got the blessing of Hollywood Records, the Jonas Brothers' label, which is owned by Disney and which sold 8.5 million copies of the band's last three albums—Jonas Brothers, A Little Bit Longer, and Lines, Vines and Trying Times.

But the boys in the band aren't really boys anymore, and the sales of their recent albums have slipped slightly. Their 2009 Disney Channel sitcom, Jonas L.A., didn't catch on with viewers and was canceled after two seasons. Their debut film, Jonas Brothers: The 3D Concert Experience, was a disappointment, earning just over $19 million.

The thinking at Disney HQ seems to be that a solo turn by Joe might be a way for the Brothers to recapture their maturing fan base and possibly develop a new one. "We're not breaking up, we're just taking a break," Joe says. "I really have a hope for the fans that got older and went, 'You know what, I'm really not into the Jonas Brothers anymore,' that I'm able to catch their ear again with my project and they're able to go, like, 'Hey, this is cool stuff, I'm happy listening to this, I'm not embarrassed listening to this.'"

"I'm wildly supportive," says Rich Ross, chairman of Walt Disney Studios. "Going solo is a very good idea for Joe at this age. It's like graduating from college."

But will Joe Jonas be believable as a real rock star? Can the fans ever forget that they loved him in fourth grade?

"I look at Joe's scenario as kind of like when Justin Timberlake broke out of 'N Sync," says Rob Knox, a producer working on Joe's solo project who previously teamed up with Rihanna and Jamie Foxx. "Justin was 21 when he came out as a solo artist. Joe is coming to producers who know how to create that edgier pop feeling. We're not doing any boy-band songs."

What they are doing, Joe says, is an eclectic mixture of "electro indie pop rock." "It's Joe's album, it's not just something put together for him," says Danja, another veteran producer on the project, whose past work includes Timberlake's FutureSex/LoveSounds. "He's collaborating with the writing. He's very different from what you'd expect. All I can say is he's an adult man. He has a rock-star edge about him."

• • •

If Nick was always the cute Jonas, and Kevin the other Jonas, then Joe was the sexy one. The shrieks of the Brothers' 10,000-plus crowds are usually induced by his hip-swiveling-and-mic-twirling routine.

"Being on stage makes me come to life," Joe says. "When all eyes are on you, they're watching every move you make."

His gyrations have apparently caught the eyes of a number of fetching young female entertainers. He's dated the troubled Disney star Demi Lovato ("I wish her the best") and the actress Camilla Belle. Taylor Swift was so bitter after their breakup that she wrote a song about it ("Forever & Always") and went on The Ellen DeGeneres Show, in 2008, to complain that Joe had dumped her in a phone call that lasted 27 seconds.

Joe countered by saying that it was Swift who had hung up on him. Now he says, "I think all artists have a right to write about what happens to them. But," he adds with a smile, "I have a right to write about things too."

He won't say whether his album will contain a Swift rebuttal—just that there will be songs about "different love scenarios that I've been through, breakups, hurts. Me hurting somebody and feeling bad about it. I think there's a lot of scenarios where people might wanna hear my side of the story."

But who would break up with Joe?

"Some guy," he says with a laugh.

It's a nod to the gay rumors he's been fending off ever since he got into a verbal altercation with some taunting paparazzi earlier this year. "There's nothing wrong with being gay," he says now, "but I'm not." Adding to the buzz, he dressed up in a leotard and heels and danced to "Single Ladies"—to comic effect—to square a sports bet with some buddies. He got the idea from his fans. The video of his performance got more than 25 million hits on YouTube.

But he really did have his heart broken; it was about two years ago, and the young woman was someone in the entertainment world. "I won't say her name," Joe says. "But I was in a relationship, and we tried to work things out, and she, you know—I was really upset because she—she broke up with me." A sadness lingers in his voice.

By contrast, his relationship with Ashley Greene, who's 24, "feels good," he says. "I think what works about it is she really puts my feelings first. She understands my busy schedule. She'll fly out to my shows—she's been to places in South America that I can't even pronounce." And in January, he visited her in Baton Rouge, Louisiana, while she was shooting the next two installments of the Twilight series, Breaking Dawn: Part I and Part II (Greene plays the psychic vampire Alice Cullen). He also flew to Jacksonville, Florida, to meet her parents. "Her dad can drink me to shame," Joe says. "He's awesome."