The Clean Teen Machine

• Video: Behind the Scenes at the Jonas Brothers' Cover Shoot

It's nearing 8:00 on a sweltering night in Phoenix, and as the temperature mercifully dips below 100 degrees, a trillion swelling hormones have collected at the Cricket Wireless Pavilion to experience the Jonas Brothers. Among the undersize pilgrims in attendance are Jordan and Jackie, a pair of blond preteens from nearby Scottsdale. Moments ago, they met the Jonas Brothers in person at a "meet and greet" photo op, and now they stand red-cheeked, quivering and sobbing uncontrollably, as if they've been told that Disneyland just burned down, with the world's supply of kittens and baby pandas trapped inside.

"Omigodomigodomigod," Jordan says, holding her arms aloft and shaking her palms in the air.

"I got tingles in my body all over the place, because I. Just. Met. Nick. Jonas," Jackie says.

"I've wanted to meet them for, like, my whole entire life," Jordan says.

How old are you?

"Ten."

It's like this everywhere. At a Jonas Brothers concert in Dallas, I meet a 17-year-old girl named Lauren who hosted a red-carpet premiere party at her house for the brothers' recent Disney Channel movie, Camp Rock. ("Even my girlfriends who weren't into it, we made them dress up," she says.) I meet girls from Baton Rouge, Louisiana, one of whose dad drove them seven hours to the concert ("He wore an iPod"). I meet many fans who, like the Jonases, wear "purity rings," vowing chastity until marriage. I meet a precocious 11-year-old named Hannah (not Montana) from New York. "We have to teach people to like the Jonas Brothers," she instructs me, finger wagging. And why is Hannah from New York in Dallas?

"To see the Jonas Brothers," she says. "Duh."