McWilliams: “I’m getting a lot more out of college the second time around.” Photograph: Lee Pellegrini

In 1979, at the age of 24, John McWilliams ’07 was one of the young­est traders on the floor of the American Stock Exchange. In 2001, after a successful and varied 27 years on Wall Street, he retired—he’d achieved the goals he set, he says. Only one hole remained in his résumé: At age 20, close to failing out of Boston College, he’d left school in the middle of his junior year.

Two years ago, McWilliams returned to campus to complete the bachelor’s degree course he abandoned in 1975. He has been a full-time undergraduate in the Carroll School of Management (CSOM), sitting among classmates who are less than half his age and in many cases, he says, more than twice as academically prepared. He is due to graduate this May at the age of 53 with a degree in finance—one of only four CSOM undergraduates over the age of 40 to receive a diploma in the past 10 years. It was “unfinished business,” he says. “When you’re self-made, you often miss the foundation. Strip away the suit and tie and you realize just how much you are missing.”

Sipping coffee at a table in the noisy Lyons Dining Hall, McWilliams looks more like a professor than a student, save for the overstuffed backpack at his feet. In his pressed khakis and tucked-in blue button-down shirt, he is one of the few male students in the midmorning crowd without a baseball cap and one of even fewer without stubble or a beard.

He has grown accustomed to standing out, he says, and has come to enjoy the role of “elder student.” Talking with young people just starting out—sharing career advice, life advice—has been one of the best parts of returning, he says, waving at a few students walking by, classmates from his morning finance class. “I can tell you right now, I’m getting a lot more out of college the second time around.” As a finance major who’s also taken painting, drawing, English, and film classes, McWilliams says, “I’m getting all the stuff I can possibly fit in.”

McWilliams’s first years at Boston College, in the 1970s, were a different story. As a freshman in 1972, he says, he was a long-haired 18-year-old “who just wasn’t ready for school.”

“I spent my first years here trying everything except studying,” he recalls. “Classes were an afterthought. . . . I wasted a lot of time.”

By junior year, McWilliams was, by his own admission, mostly absent from school—“I spent more time working”—he was holding down two off-campus jobs at the time—“and partying. . . . School just wasn’t a priority. But I always had a knack for making money,” he says. “I was the kid who, at age six, was fishing coins out of the subway grates with string and chewed-up gum.” That instinct led him to a back-office job at a Wall Street firm during the summer after his freshman year. “I loved the chaos, the buzz, the excitement,” he recalls. A few months after leaving school, he inquired about returning to the company, and learned that another firm, Spear, Leeds, & Kellogg Specialists, LLC, was looking for a summer office intern. He took the six-week position at $100 a week, and he asked his colleagues to teach him how to work the books—capture trades, record accounts—during lunchtime.

“At that young age, I could run numbers through my head faster than most people now can type them into a calculator,” says McWilliams—a helpful skill, he points out, in the age of slide rules and paper record books. Management quickly picked up on his gift and by the end of the summer, he was working as a frontline trading assistant, a rare opportunity for someone of his experience. Within three and a half years, he became a specialist trader on the floor of the American Stock Exchange.

From there, McWilliams’s career took off. He oversaw major corporate investments in New York and Chicago, and in 1981 started his own execution firm with a seat on the New York Stock Exchange (NYSE). Six years later, he sold the seat and moved to San Francisco, where he joined an investment firm as a vice president in equity trading; he was subsequently asked to return to the NYSE to manage the trading floor for the firm, and went on to partner as a senior trader at two other companies.

In 2001, when McWilliams retired, he and his wife and young son moved “about as far away from Wall Street and the Northeast cold as possible,” to rural Ojai, California, where they’d fallen in love with a property while on vacation.

As a young man making money, McWilliams says, it took him a while to feel he’d missed much at college. “But when you’re raising a curious child, you suddenly realize you don’t have a lot of the knowledge you want to impart. . . . You begin to see what a narrow corridor you’ve been living in.”

Two years ago, when McWilliams’s son was accepted to a Massachusetts prep school and the family moved from California to New England, “the stars began to line up,” he says. “My education is actually an offshoot of my son’s.” He called Boston College and began what would become a series of long conversations with Richard Keeley, the associate dean for undergraduates at CSOM.

“Ninety-five times out of a hundred, these calls end up going nowhere,” says Keeley, “but John really wanted this.” Keeley suggested McWilliams spend a semester in the Woods College of Advancing Studies to reimmerse himself in the academic environment before returning full-time. McWilliams enrolled in Woods in September 2005; in January 2006, he was officially readmitted to the Carroll School with a full five-course load.

“I had to learn all the skills I needed just to learn,” he says. A hunt-and-peck typist, McWilliams initially found himself behind the curve on nearly every front. “Try solving for X when you haven’t taken algebra for three decades,” he says, shaking his head. “I spent at least two or three days a week, for a while, getting tutored by students at the [Connors Family] Learning Center.”

CSOM students, for their part, have welcomed McWilliams as a classmate and a special resource. “He’s so personable, and he doesn’t flaunt anything,” says Elliott Smith, a lecturer in finance. This past semester, McWilliams was a student in Smith’s financial policy class, and Smith would often use him as a sounding board in class discussions, asking him to comment on case studies or to volunteer anecdotes. “Any kid working in a group or taking a class with John,” said Smith, “gets to learn what he’s paid his dues to learn.”

McWilliams, like many graduating seniors, isn’t sure what the future holds; returning to school, he says, was never about preparing for a career. “It hasn’t really struck me I won’t be going to BC anymore,” he says. His immediate plan is to spend time with his wife and son. “Who knows after that—maybe I’ll reinvent myself. I’d love to counsel kids,” he says. Pause. “And Silicon Valley is fascinating.” He pauses again. “But I might still trade,” he says, smiling. “I miss the rush.”

Read more by Cara Feinberg