As far as glitzy New York City fashion parties go—you know, the kind that attract It Girls like Sienna Miller and Anne Hathaway—the Oct. 25 Bergdorf Goodman bash for the fashion line Marchesa had a decidedly understated feel. The table centerpieces featured hydrangea blooms, the place cards were standard white, and the 80 or so guests sipped blush champagne while nibbling on crab cakes.

In other words, it was the perfect, subdued setting for showing off the real stars of the night: Marchesa's exquisitely elegant gowns, which during the past two years have emerged as the red carpet look of choice for actresses ranging from Felicity Huffman to Mischa Barton. To be sure, part of the label's appeal for big events like the Golden Globes is "that it has this subtle, vintage glamour about it," says stylist Rachel Zoe. But Hathaway offers a more simple explanation. Recalling a recent charity event to which she wore a black-tulle bubble Marchesa gown, she says, "I had just gotten off the plane, was so exhausted, and I knew that my face looked horrible. But I was like, 'Damn—my dress looks good!'"

That's the reaction best friends Georgina Chapman and Keren Craig—the designing duo behind Marchesa—have been eliciting from stars ever since Renée Zellweger chose a red silk, sari-inspired dress for the 2004 London premiere of Bridget Jones: The Edge of Reason. And as they mark their two-year anniversary as business partners, Chapman and Craig not only have their Marchesa line (which ranges from $2,500 to $16,000) but also a lower-priced label, Notte by Marchesa (which starts at $600), and a newly expanded studio and showroom in Manhattan's meatpacking district. The duo, both 30 and natives of the U.K., first met in 1995 at London's Chelsea College of Art and Design. Chapman went on to study costume design—she also modeled to pay her way through school—and Craig majored in textiles. "We used to go to a lot of parties, and we'd always work with each other to make our own dresses," says Chapman. Those dresses got noticed by style icon Isabella Blow, who encouraged them to set up shop. As for the decision to name their label after Marchesa Luisa Casati—an eccentric Italian aristocrat who during the early 1900s was known as "the most scandalous woman of her day" for such gestures as wearing live animals as accessories—well, it was a way to add some flash. "'Chapman and Craig' sounded like builders or dentists," she adds.

With awards season around the corner, the pair are bracing for another worthy project: designing a wedding gown for Craig, who got engaged to longtime boyfriend Piers North, an art director, last February. As for Chapman—who for the last two years has been dating movie producer Harvey Weinstein, 54, the former head of Miramax—she says there aren't wedding plans in her near future. "Harvey and I generally just hang out with friends, family and my dog Rocky. Very boring!"

So what passes for excitement? Take a recent evening when Chapman and Craig walked past Bergdorf and spotted one of their gowns in the display windows. "We didn't even know it was there," Chapman says. "We stopped and took photographs—we were posing in front of the window taking pictures!"