Mothner was a freshman considering a career in banking when he started a web marketing business in his Gold Coast dorm room to earn extra cash. The service allowed small businesses to list their websites with some 200 different search engines.

By the time he graduated, the company, WPromote, was bringing in about $100,000 annually—and thoughts of banking were left behind. The next year Mothner hired Michael Block ’04, a childhood friend and Dartmouth water polo teammate who is now the company’s chief operating officer. They focused on placing clients’ ads with a search engine that had just gone public: Google. “Our original tagline was, ‘Helping businesses succeed online,’ ” Mothner says. “While we don’t use those exact words anymore, that is what we still do today. We’ve just evolved in size and scope and complexity.”

Today it’s a full-service, integrated digital marketing firm—which Ad Age and Fortune call one of the best places to work in the industry—with more than 600 clients and $50 million in annual revenue. Kelly Mulvey ’93, who joined as chief financial officer about two years ago, has steered the El Segundo, California-based company into acquisitions. With 330 employees and seven offices, it’s the largest private digital marketing company in the country. Mothner says “sweet-spot clients” are like WPromote itself: growth-oriented companies that are “looking to take on 800-pound gorillas” in their industries. The firm also specializes in prompting large, established brands to think more like “challenger” brands.

“We try to skate where the puck is going, not where it’s at,” Mothner says. “We grew on the backs of Google and then Facebook, but we’re agnostic as to what happens next.”