During her undergraduate study at Lehigh University, Lauren Crampsie took a communications course in which the professor mandated all students read "Ogilvy on Advertising," the tome penned nearly three decades ago by ad legend David Ogilvy. Little did she know then that it would be helpful preparation for her career at the WPP shop, where she has fast-tracked to the role of CMO.

Ms. Crampsie, 31, got her first taste of the media and advertising worlds after a final-hour decision to defer her acceptance into law school. She dabbled in assistant jobs at ABC and at the "Today" show before joining Ogilvy as new-business coordinator. Two years later, former Ogilvy senior exec and now Googler Andy Berndt offered Ms. Crampsie her first big break: control of the New York office's new-business department.

Then last year in a surprising move, Ogilvy North America Chairman John Seifert turned to Ms. Crampsie to take the role of CMO of the agency's North American operations. It was a decision that symbolized not only the appreciation that Ogilvy has for the next generation of ad talent, but also a desire to fuse together the agency's corporate reputation and new-business efforts. The move has already paid off; Ms. Crampsie was key to bringing in the Gap account.

"You go through 50 or 60 pitches a year, and you see clients come and go," Ms. Crampsie said. "But Gap was an example of a client where I really felt like it was a personal mission to really help that brand."

Ms. Crampsie said that in her ad career, Ogilvy Chairman Shelly Lazarus has been her biggest source of inspiration. The admiration is mutual; when Ms. Crampsie was named CMO, Ms. Lazarus wrote her a letter saying that "you're the perfect person to keep Ogilvy famous."

Said Mr. Seifert: "She is an incredibly talented person, full-stop. ... Sometimes Ogilvy has had a system of gates before you can get to the next level, and I wanted to cut through all that . We would never have built an Ikea house in our theater without someone like Lauren. With the Gap, she can sit in the room with the CEO Glenn Murphy, or she can sit with the most junior product designer and talk about life in the clubs."