No one can be sure precisely when it was that entrepreneurship became "professionalized"--becoming not just the default play by big-business outsiders but a full-on legitimate career choice for men and women with graduate degrees, fast-track corporate CVs, low risk tolerances, and good haircuts. No one can be sure, but it might have been May 1, 1986, the moment when Tom Stemberg opened the first Staples.

Stemberg, though only 37 at the time, had already constructed an enviable resume. Harvard M.B.A., head of a tiny start-up, division president at a billion-dollar grocery chain. He knew retail at street level and corporate finance on the floors where the elevators end. And he'd noticed, in the years leading up to his Staples idea, how the composition of the business world around him was changing. All those new small businesses that needed supplies no one was prepared to sell them. All those customers no one was ready to serve. He saw his opportunity. He attacked it.

Only he did it the way so many pros have done it since. Planned out, disciplined, well funded, well advised. From the start he thought big. "I envisioned 24 stores, $120 million total revenue," he says. A bad projection, it turned out. Last year Staples had sales of $11.6 billion. Depending on your point of view, he and his company either rode the entrepreneurial boom or helped enable it. Probably both. And all the while, Stemberg was pulling off another managerial trick: Rare among entrepreneurial founders, he remained CEO and driver of his company through all the stages of its growth, from infancy into the double-digit billions (until appointing a new CEO in 2002). "I think I was able to do that for one overwhelming reason," he says now. "I wasn't a rookie to the various phases of business. I'd run a start-up before, I'd run a billion-dollar chain and all the phases in between. I knew what to expect." Which makes the trick sound easier than it is.

His key piece of strategic advice sounds easy too. "Never lose sight of the customer," he says. "I learned it from my first-year marketing professor, and it's still the most important thing to know." But where's the competitive advantage in that these days--hasn't every company already learned to put the customer first?

Not remotely, says Stemberg. "I get maybe 10 business plans a week," he says, "and for every 100 of them, 95 are an idea looking for a market. Only five address a market opportunity in need of a solution. So if everyone's talking about serving customers, they're sure not understanding how to do it." You can hear Stemberg's distaste as he fingers the wrongheaded 95%. And you can tell what he's thinking as he describes their mistake. He's thinking: How unprofessional.--Michael S. Hopkins

Michael S. Hopkins is an editor-at-large.