Girl Power

Hilary Duff is sick and tired and self-medicating with M&Ms. It's a Tuesday afternoon, and the 15-year-old break-out star of the Disney Channel's "Lizzie McGuire" is doing a guest appearance on "George Lopez." She's sick from a mysterious tummy ailment. She's tired from a recent three-day press junket. And she's sick and tired of algebra. Hilary snuggles into a beanbag chair and pops some of the candy-coated uppers, which do seem to help. She even refrains from rolling her eyes when the on-set tutor tells her, "When you learn something new, just hang it on your idea tree." Then, when talk turns to "The Catcher in the Rye," she gets perky. "Holden's kind of annoying me," she says. "I mean, he keeps talking about people being fake and phony. But really he's the phony one." OK, it's no doctoral thesis, but she's got Caulfield nailed. And, honestly, can you blame her for getting annoyed? Something as self-indulgent as a nervous breakdown would get her way off schedule.

Home-schooling from 8 a.m. to noon. Voice lessons from 1 to 2. Recording sessions from 3 to 6. And "no time for boys" since things went sour with pint-size pop star Aaron Carter. That's a light week for the tween icon, whose show is now one of the highest rated on basic cable. Lizzie's fizzy middle-school misadventures, like buying a bra and scoring a first kiss, are always sweet, never syrupy--making the show palatable for parents and even twentysomethings. Duff, who's got a giddy charm and unexpected vulnerability in person, has established herself as the best actress of her generation, easily outclassing the Olsen twins and Nickelodeon's Amanda Bynes.

Now, with just a dozen "Lizzie" episodes left, Duff's headed to the big screen. Her film debut, as the damsel in distress opposite Frankie Muniz in "Agent Cody Banks," opens this week. It's just a supporting role in the cute "XXX" knockoff, but she's awfully convincing as the prettiest girl in high school. (Typecast much?) In May, Duff will fall for a sleazy Italian rocker in "The Lizzie McGuire Movie." And even as an untested leading lady, she'll take home a whopping $2 million for a modern-day "Cinderella Story," which her mother, Susan, will coproduce. The ink's barely dry on that contract, but at "George Lopez," Mom's back on her mobile phone: "You tell them we've got the movie to take Hilary to the next level. If they don't want it, the other studios will be all over it like a duck on a June bug."

So, obviously, the Duffs are from Texas. A makeup artist turned rancher, Susan insists she "never wanted to be a stage mom." (Older daughter Haylie is also an aspiring actress and singer.) But, five years ago, when the kids begged to be performers, she loaded them all into the family Acura--along with a hermit crab, a gerbil, two goldfish and a rabbit--and drove the 20 hours from Austin to L.A. Her husband, Bob, stayed behind to run a string of 53 convenience stores, but promised to fly in every three weeks. After winning the lead in "Casper Meets Wendy," Hilary landed at the Disney Channel. "When we were casting 'Lizzie McGuire' we called her in four times," says Rich Ross, president of the channel's entertainment division. "She wasn't doing anything wrong. She just wore such great outfits, and we wanted to see what she'd come in with next."

TV executives aren't always so supportive of Hilary's fashion sense. One Monday afternoon, a rooftop video shoot for Duff's new single, "Why Not," gets delayed while the Disney folks e-mail each other pictures of her Jean-Paul Gaultier shirt, trying to decide if it's inappropriate. Never mind that it's the kind of blouse Britney would wear to church--long-sleeved, with small holes that suggest more than they reveal. "It's not like my boobs are exposed or anything," she says. "This is what I'm comfortable in." They finally reach a compromise: the holes cannot reveal her actual bellybutton, just the skin around it. That's how you come of age in Hollywood, painstakingly negotiating your sexuality with an army of handlers. "It really is a strange life, always surrounded by men who don't want to hang around with a 15-year-old girl," her mother says. "The ones who do want to hang around, I have to be really careful with."

Under Disney's--and Mom's--protective gaze, Hilary is now focused on life after Lizzie. "Since I'm getting older, it's hard to find parts that are wholesome," she says. "I know I can handle dramatic roles, but I don't think I should have to play a young mother on crack to prove it." While she waits for a grown-up role, Hilary tries to find time for the teenage things--school dances, lunch with her sister, bouncing on a trampoline (a favorite pastime that'll do nothing to dissuade the older men). "Sometimes I just wish I had a day off," she says wistfully. "I really need to clean my room."

Yes, seven months from a driver's license and counting the days--TV's hottest tween star is sweet and well-adjusted. Go ahead, hang that on your idea tree.