NEXT: Mary O'Keefe

"This has been the most exciting year," says Laura Lang, wearing one of those communicable smiles you can actually hear over the phone. "So much has transpired in the agency, and we feel terrific momentum."

Laura Lang, CEO, Digitas USA

It's little wonder that the CEO of Digitas USA is smiling. Last December, Digitas was acquired by Publicis Groupe for $1.3 billion. Since then, the digital-marketing agency has snapped up business wins in several major product categories.

In just the first quarter, Digitas was named interactive agency of record for Miller Brewing Co., General Motors Corp.'s Saturn and Sara Lee Corp.

Under Ms. Lang's leadership, Digitas is also ramping up its efforts in the health sector, which she calls a "hugely exciting growth category." Digitas had already handled pharmaceutical marketers but in April absorbed a sibling agency, health-care-marketing specialist MBC, creating Digitas Health. MBC co-founder David Kramer, now CEO of Digitas Health, reports to Ms. Lang.

Their goal is to change the way pharmaceutical companies reach consumers by creating "experiences that open up the right kind of discussion between physicians, patients and their caregivers," says Ms. Lang, 51.

With an MBA from the Wharton School of the University of Pennsylvania, "I tend to think from a strategic point of view," Ms. Lang says. Before joining Digitas in 1999, she showed those analytical chops as president of Marketing Corporation of America, providing strategic consulting for national and global marketers. Previously, she was senior VP-group manager at market-research and consulting company Yankelovich Clancy Shulman.

"She's the kind of agency executive whom clients follow," says Marc Lefar, who worked with Ms. Lang while he was chief marketing officer at Digitas client Cingular Wireless. Over the years, Mr. Lefar has developed a list of agency executives whose insights he continues to seek. "She's on that list," he says, "and I think she's on that list for a lot of marketers. She's someone you want to keep in your Rolodex as part of your array of marketing assets."

When Ms. Lang isn't being followed by her fan base, she's making music -- learning to play the piano her husband gave her for their anniversary. Given all the strategic, quick thinking she does on the job, it's no surprise that Ms. Lang most loves improvisation. "You've got to just let it flow," she says.