FORTUNE — How do you define success?

That’s the question at the core of an exhaustive research project by Timothy Judge, a professor of management at the University of Notre Dame’s Mendoza College of Business. “Despite their many accomplishments, ambitious people are only slightly happier than their less-ambitious counterparts, and they actually live somewhat shorter lives,” says Judge.

His study tracked 717 go-getters, born in the early years of the 20th century, and measured ambition, achievement, and various indicators of health and happiness at key points in the subjects’ lives, from childhood into young adulthood and beyond.

Many in the group graduated from Harvard, Yale, Princeton, Stanford, and other prestigious schools, and then went on to demanding, high-status, highly paid careers. Yet, when compared with a control group of more laid-back peers — folks with the personality profile psychologists sometimes label Type B — the high-achieving group was not markedly happier. What’s more, the slackers, on average, outlived the high-achievers.

“We discovered that ambition has, at most, only a very slight positive effect on life satisfaction, and actually a slightly negative impact on longevity,” says Judge. “So, yes, ambitious people do achieve more successful careers, but that doesn’t seem to translate into leading happier or healthier lives.”

Although the study doesn’t address the reasons for higher mortality rates among ambitious people, Judge speculates that “perhaps the investments they make in their careers come at the expense of the things we know affect longevity,” such as “healthy behaviors, stable relationships, and deep social networks.”

Note to parents: Pushing kids to aim for the stars, get into a prestigious school, and pursue a high-powered career may not do them any favors in the long run.

“If your biggest wish for your children is that they lead happy and healthy lives, you might not want to overemphasize the importance of professional success,” says Judge. “There are limits to what our ambitions can bring us — or our kids.”

The study, “On the Value of Aiming High: The Causes and Consequences of Ambition,” will appear in a forthcoming issue of the Journal of Applied Psychology.