This Summer's Biggest Act? The Jonas Brothers

Their videos are reminiscent of the Monkees. One of them has a strut like Mick Jagger. And their screaming fans? That's déjà vu of the days of Beatlemania.

They're inching toward adulthood -- one is still too young to drive -- but the Jonas Brothers are a household name for 'tweens, teens and the parents who love the brothers' wholesome image.

Kevin, Joe and Nick burst onto the scene last summer as the opening act for Miley Cyrus. One year later, the Wyckoff, N.J. natives got top billing on their own tour that's playing to sold-out audiences around the world.

Watch the Jonas Brothers perform live on "Good Morning America's" Summer Concert Series.

The Jonas BrothersPlay

If you haven't heard of them, you were probably born before Bill Clinton was in the White House.

If magazine covers are a measure of a group's popularity, the brothers are huge. People magazine devoted a whole issue to them, they have appeared on every single cover of Tiger Beat for more than a year, and just this week landed on the cover of Rolling Stone.

Broadway Dreams

The Jonas Brothers' road to stardom began years ago when a young Nick Jonas, who is now just 15, started landing roles on Broadway. He's appeared in "Les Miserables," "Beauty and the Beast," "A Christmas Carol" and "Annie Get Your Gun."

Older brother Joe Jonas, 18, followed in his footsteps with a part in "La Boheme."

"I didn't want to sing originally," Joe Jonas said told ABC News' Juju Chang. "I was like, 'There is no way you will catch me singing,' and I ended up being in an opera on Broadway."

They all grew up singing songs as a family, and eventually Nick Jonas caught the eye of a record company recruiter. Columbia Records signed them to a recording contract, but after the first album and a shake-up in management at the label, they were dropped.

Hollywood Records, which is owned by the Walt Disney Company, the parent company of ABC News, immediately signed the boys. One reason was the savvy way the young men were using the internet. They had more than 30,000 fans on their Web site.

Since then, they've been "Living the Dream," as they've put on display on their reality show. They've also had a hit song titled "S.O.S.," a television movie called "Camp Rock," and a sold-out tour. Their new album, "A Little Bit Longer," will be released on Aug. 12.

Staying Squeaky Clean

People magazine writer Sharon Cotliar said that when she suggested a story on the brothers 16 months ago, she had a hard time convincing an editor that they were worth the magazine's coverage.

Now they join a list of squeaky-clean acts that moms and dads feel comfortable sharing with their kids, especially at a time with scandals-du-jour are splashed all over the news and Internet.

"I think for many parents it's great for them to be able to take their daughters to these concerts and know that these are boys who really have values," Cotliar said.

"They have talked about wearing purity rings, they talk about going to church, their father is a minister," she said. "Their mother and father travel with them. So these are kids that parents feel their daughters can support."

No Time for Romance

Kevin Jonas, 20, gave "20/20" a private tour of the group's bus, including the shower -- something scores of pre-teen girls only dream of.

But while the boys spend a significant of time on that bus, that doesn't mean there's no time to be boys.

The boys' father, Kevin Jonas, also the band's manager, said love is a distraction. A recent trip to the dentist, he said, ended with a police escort because of all the girls who swarmed the building.

"You know, somebody asked them the other day 'So if you actually had a girlfriend, would you tell us?'" he said. "And the answer was, 'No, I wouldn't tell you.'"

Denise and Kevin Jonas have seen too many examples of what not to do, so they try to keep the drama surrounding their sons to a minimum.

"We've tried to show them examples of people that have basically started with success and found the road difficult," dad Kevin Jonas said. "Maybe they went off track, hit a hard streak, some people were disloyal, they stopped trusting people. And look at where they ended up."

Behind the Scene

Nick Jonas has incorporated his own personal struggle into his music. Just as the band was gaining attention, he was hospitalized and eventually diagnosed with Type 1 diabetes. He later wrote a song about the experience that he sings at every stop on the summer tour.

As far as school, Kevin Jonas has already graduated from high school and the other boy are home-schooled, or rather, bus-schooled.

Despite spending so much time together, they really are three separate young men. Michelle Tomaszewski, who used to work with Britney Spears, is in charge of putting their look together.

"Kevin is the more kind of aristocratic rock-star," she said, adding that he likes to wear clothes that make him "a little bit more grown up."

Joe, she continued, "likes to wear the red pants or neon pants. He's more of, like, the risk-taker."

And the youngest Jonas brother, she said, is more subdued, calling him a "kind of laid-back, like, chilled guy in a T-shirt with a leather jacket and jeans."

If you want to know what else is happening with the Jonas Brothers, they blog every day on their Web site. Staying in close touch with their fans seems to be a strategy that is paying off.