Visionary. Early on, Drayton saw that while government can be inefficient and the private sector motivated by profit, the nonprofit sector was ripe to provide change. Indeed, this "third" sector, or so-called citizen sector, as Drayton calls it, has exploded--70 percent of registered nonprofit groups in the United States are under 30 years old. "More and more people want to do this kind of work," says Drayton. "We are creating the jobs; the salaries are going up. We are desperate for managers."

Much of the change in the citizen sector can be attributed to Drayton, who made it his life's work to not only expand Ashoka but also develop the field as a whole. "Bill was the pioneer; he really laid the foundation for the rest of us," says J. Gregory Dees, professor at Duke University's Fuqua School of Business. When Dees attempted to introduce the first social entrepreneurship course in business school, he was rebuffed. Nearly 15 years later, it is a common offering at leading business schools like Harvard, Stanford, and the University of Chicago.

In many ways, Drayton's life has been a long road toward learning how to change systems. At Harvard, he founded Ashoka table, where students could ask government and industry leaders how the world really works. Drayton continued at Oxford as a Rhodes scholar and graduated from Yale Law School. Later, at the consulting firm McKinsey & Co., he learned about public policy and industries. While advising New York City, he created the nation's first nicotine tar tax. In the Carter administration, as assistant administrator of the Environmental Protection Agency, he pioneered the concept of emissions trading, in which companies or whole countries can reduce their allotment of pollution emissions by selling those allotments to others. During the Reagan years, Drayton successfully used the media to stop the administration from dismantling the EPA.

Though he characterizes himself as a moderate introvert, Drayton has the innate charisma of great leaders. Former Indiana Rep. Lee Hamilton, who cochaired the 9/11 commission, recalls that he had misgivings when the 21-year-old Drayton volunteered to help on his House campaign in 1964. "He looks like a scholar, and I said to myself, 'How will he fit in with Hoosiers--with Indiana farmers?' " Drayton was able to charm local party operatives as well as farmers, and he helped Hamilton win.

The charisma stems from genuine interest and skillful listening. Kyle Zimmer, a board member of Ashoka, remembers meeting Drayton when they worked on Walter Mondale's presidential campaign in 1984. "It was tremendously empowering to be around Bill. You felt as if when you talked your ideas were considered." Zimmer describes similar scenes at Ashoka meetings. "The first time I sat at a meeting, an intern raised a hand, and I thought, 'You have got to be kidding; that's someone with moxie.' But it happens repeatedly. Bill appreciates people who are thinking and engaged and he doesn't care if it's someone very influential in Washington or a tribal leader in some very remote area of the world."