Which, for Posen's fans, means feeling sexy, strong and, like the designer himself, ready to groove—qualities that have helped make his draped, dramatic creations a hit with young Hollywood, including longtime pal Claire Danes. With A-listers like Berry and Moore joining the Posen posse, the 22-year-old—who still lives with his parents in the SoHo loft where he grew up—has become one of fashion's rising talents. "What is really beautiful about his clothing is that it is one of a kind," says actress Anna Paquin, who donned Posen's "punk-rock Tinkerbell dress" for a recent photo shoot. Adds Joan Kaner, senior vice president and fashion director for Neiman Marcus, where Posen's $500-and-up line has been a smash since hitting stores a year ago: "He has done pretty and very feminine clothing, and women have responded."
In part, perhaps, because his clothes are designed with an eye toward women of all shapes. "It's really important to look at the beauty of every body," says Posen, who shuns the fashion industry's size-O standard. "Clothing should empower the woman." It did just that for Marissa Jaret Winokur, the star of Broadway's Hairspray, who wore a ruffled Posen gown-created in just two weeks after the original designer backed out—to the Tonys in June. "Usually designers think they know what is best," says Winokur. "But Zac listens to what you say."
Posen cites his mom, Susan, 57, an attorney and now CEO of his company, Outspoke, and sister Alexandra, 30, his creative director, as his inspiration. Growing up in New York (dad Stephen, 63, is a painter), Posen recalls, "I used to steal yarmulkes from my grandparents' synagogue so that I could make bell dresses for dolls." Although his parents encouraged his passion for fashion, "it was definitely something, when you're a boy, that you're ashamed of," he says.
Posen's self-confidence grew with his style, and at 16, he spent a summer at New York City's Parsons School of Design. An internship with designer Nicole Miller and a stint at London's Central Saint Martins College of Art and Design followed. His talent was evident early: At Nicole Miller, he says, "I watched the first thing I drew [a white poplin shirt] go into production."
By the fall of 2001, Posen was ready to launch his own line, setting up Outspoke in his parents' living room. "In a small business you have to put your resources in the right places," says Susan of her son's no-rent living arrangement. The following year, with the aid of a $20,000 grant and an attention-grabbing runway show, business took off. His clothes now sell at such upscale retailers as Bloomingdales and Barneys New York. Meanwhile the designer, who hosts dinner parties for pals when he's not working, is setting his sights on future clients. "I love Madonna," he says. "I like Oprah Winfrey, Anjelica Huston, Tina Turner." If you're interested, ladies, give him a ring. He'll be at his mom and dad's place.
Rebecca Paley in New York City