(FORTUNE Magazine) – Ah, summertime, when daydreams turn to leaving the corporate world behind, and maybe joining a nonprofit and trying to save the world, or at least some small corner of it. "We're seeing an enormous increase in the number of lawyers and businesspeople who've been madly in pursuit of money for years and are suddenly asking, 'Is that all there is?'" says Robert Egger, who has written a book called Begging for Change: The Dollars and Sense of Making Nonprofits Responsive, Efficient, and Rewarding for All (HarperBusiness, $24.95). "The maturing of baby-boom businesspeople is a huge potential energy boost for nonprofits. The real question is whether nonprofits are ready for the influx of new talent." As it happens, charities are hiring at a healthy clip. A recent survey by Kintera (www.kintera.com), an Internet company that helps non-profits with raising money and building networks of volunteers, says that 76% of them plan to maintain or increase their headcount this year. What's more, a leadership vacuum looms. In New York City, for instance, 45% of social service organizations are led by executives who are planning to retire within the next five years, and most have no succession plans, according to the United Way chapter there.

Nonprofits need the know-how that businessfolk can bring, says Egger, a former nightclub manager who runs a national network of food banks, shelters, and job-training programs for the homeless (see www.dccentralkitchen.org), based in Washington, D.C. Says Egger: "Charity in the U.S. is an $800 billion industry that is way overdue for an overhaul. We need greater efficiencies and strategic thinking." But hold on. Before you saddle up your white charger and ride to the rescue, he has a few important tips for you. "Most people come into nonprofit work with unrealistic expectations, and then get terribly frustrated with the realities," he says. One of those realities: Competition for funding among the two million registered charities in the U.S. is so fierce that you'll spend most of your time fundraising. Another one: Decisions in the nonprofit world tend to get made by consensus and, Egger says, "only after endless chatter." You'll need patience--and humility. "Businesspeople have a certain arrogance sometimes," notes Egger. "They come in saying, 'Here's how I made my millions--now let me show you how to run this.' That approach doesn't work. You have to understand the issues and work through the existing culture to achieve incremental change."

Above all, be ready for a cut in pay. "You have to come ready to give, not take," says Egger. Since the average donor to charity makes between $30,000 and $50,000 a year, and many also do volunteer work free, "asking them to pay somebody $150,000 a year to run the thing is really asking a lot," he says. You may find the work rewarding in other ways. Says Adam Kaufman, a former business owner who now runs a Cleveland-based medical nonprofit called the IOS Foundation (www.iosmed.org): "There's nothing like helping to save a life. The payoff is immeasurable in dollars. It's an incomparable joy."