Most top execs of young fashion labels would kill for the opportunity to be carried by Bergdorf Goodman, the renowned luxury department store, but not Wen Zhou of 3.1 Phillip Lim.

When Bergdorf buyers requested Lim’s line in the spring of 2006, the label’s sales were skyrocketing. But C.E.O. Zhou was concerned that taking on another major customer at that time would overwhelm the company’s overseas manufacturers or worse, flood the market with too many clothes and have her fledgling label’s brand diminished by its appearance in the discount bin.

“We wanted to cement our feet in the market even more, really take care of the retail doors that we were already in,” Zhou says.

Zhou held Bergdorf executives at bay for more than a year before finally agreeing to take on a relatively small initial order that could increase over time. Bergdorf will begin carrying 3.1 Phillip Lim starting in January.

It’s just this judicious approach that has put the company on a fast track to profitability and $30 million in revenue for 2007. The press has tended to focus on the line’s sophisticated and finely crafted yet modestly priced clothes, but the secret force behind the label’s business success is a petite Chinese American woman who, at 34, is already a seasoned veteran of the fashion business.

“It’s not enough just to have very successful designs and a consumer following,” says Kate Sayre, a managing director of Boston Consulting Group, in New York, whose clientele includes fashion companies and luxury retailers. “There are plenty of designers that have products to sell but are not profitable.”

So Lim has Zhou. Introduced by a mutual business acquaintance, the pair became fast friends, starting the label three years ago, when they were both 31 years old (hence the name 3.1). Lim had just been forced out as the chief designer of a small Los Angeles label after clashing with his business partners over the line’s creative direction, and he was searching for his next design project. Zhou had experience and capital from running two other apparel-related businesses that she started herself—the import-export company Aegis and the sourcing agency Gwendolyn, which connects U.S. designers with factories in China. Upon finding out that Lim was unemployed, she immediately asked him if he wanted to partner with her on a new label.

“I just loved his aesthetics,” Zhou says. His clothes “make women feel a lot more confident.”

Lim quickly said yes. “At that point, I had nothing to lose,” he says. Zhou put up $750,000 in startup capital that she obtained from her two businesses and a loan against her apartment, and the two decided that they would target a market niche that they felt was underserved—designer-quality fashions, but at a fraction of the price. A pair of 3.1 trousers, for example, starts at about $300, while 3.1’s dresses retail for $500 to $700.

“For the quality, it’s really inexpensive,” says Terence Bogan, a vice president at Barneys Co-Op, where, Bogan adds, 3.1 is among the bestselling women’s clothing brands. “A coat would retail for $795, but when you look at the construction, the coat could easily be a designer coat at double the price.”

Within a year, according to Zhou, the label was breaking even. The exec says she’s able to keep costs low by capitalizing on the strong relationships she’s developed with factories in the U.S., Hong Kong, and elsewhere in China and by operating “without fluff,” by which she means such practices as eschewing expensive advertising in favor of cultivating positive word of mouth.

“Being in the fabrics industry for as long as I have been, you get the opportunity to meet a lot of people and get important contacts,” explains Zhou, who says her two other businesses generate about $28 million in annual revenue. “These contacts have proved to be crucial to our success.” Her work at Gwendolyn, for example, has helped her identify the least expensive, most reliable manufacturers in China.

Zhou, who grew up in a Chinese village of just 120 people south of Shanghai, started Aegis in New York in 1994, when she was just 21. Two years earlier, as a salesperson for a textile company, she had discovered that she loved not only working with the company’s designer customers but also handling and discussing the luxurious fabrics she sold.

Having grown up at her seamstress mother’s knee, Zhou realized she had an intuitive sense for talking about fabrics. She was able to tell customers about the technical aspects of various cloths, like yarn count, material, weave, and sheen, and also to describe the less tangible aspects, such as how the fabric felt against the skin, how it might drape on a silhouette, and the sensations it evoked when stitched into an item of clothing.

“I love clothes. I understand clothes,” she says. Despite her extensive experience with fabrics and clothes, she has left the design and artistic direction to Lim, focusing solely on the business side.

“She never says, ‘You can’t do this, you can’t do that,’  ” Lim says. “I have complete autonomy.”

Today, 3.1 Phillip Lim is carried in 250 stores around the world, and the company recently expanded its line to include menswear and children’s clothes. Its first boutique opened in the trendy Soho district of New York in July, and stores are planned for Los Angeles and Tokyo in 2008.

Zhou continues to run 3.1 on a relatively tight budget, with about 42 employees. When the company started, the diminutive Zhou did everything from dragging 25-pound cartons around town to picking up hors d’oeuvres for a reception when a last-minute glitch arose with the caterer. “I’m not afraid to get my hands dirty,” Zhou says, laughing.

And despite the label’s success, Zhou is not about to abandon her careful approach to growth, as demonstrated by her negotiations with Bergdorf.

“There are many manufacturers and wholesalers who are opportunistic—they want to sell as much as they can today,” says Bergdorf Goodman C.E.O. Jim Gold. “Wen’s patient, and she’s building for the future.”