Discussions are not always business-related. At Kunhardt's recent meeting, one member wanted to know whether or not to buy a beachfront property in South Florida where he could dock his boat. After a series of questions and observations— "It sounds like you fell in love with the place, but it seems like a bad investment" and "If you buy it, you should tear down the house and just keep the property"—he decided to bag the idea.

At other times, speakers provide invaluable insights. Ron Garfunkel, C.E.O. of Service Directions, a laundry-room management company in Yonkers, New York, and a longtime member of Kunhardt's peer group, recalls hearing a presentation on team-building several years ago that changed the way he ran his business. "I modeled my whole organization on that advice," he says.

If you don't get a chance to bring up your particular issue during a meeting, there's always time between sessions. Members often email each other or go out to lunch to discuss important matters.

Gary Zimmerman, C.E.O. of Creative Business Interiors, a Milwaukee designer of commercial space, attends meetings run by the Metropolitan Milwaukee Chamber of Commerce. He points to a member who recently emailed his group asking how much of a raise to give an employee. Everyone had a suggestion.

How to find the one for you? Often you can get information through a vendor, business associate, or friend; Kunhardt heard about his organization during a chat with a major supplier who was a member of a group in Chicago. Another good contact is your local Chamber of Commerce.

The website for the Edward Lowe Foundation in Cassopolis, Michigan, is another good source. It is dedicated to helping "second stage" companies—businesses with at least $1 million in revenue and at least 10 employees. It lists groups by state and runs its own meetings.

Once you've pinpointed the organization you want to join, you'll probably meet with a facilitator who will introduce you to a likely chapter. Then you'll attend a meeting, where members will ask you about your business and you'll get a chance to form an opinion of them. Soon afterward, they'll vote on whether or not to invite you to join.

It'll probably take about a year to develop a solid rapport with the rest of the group. And, of course, after a few sessions you may decide it's not your cup of tea.

Garfunkel, for example, joined a Vistage group 15 years ago only to find that the facilitator wasn't running as tight a ship as he would have liked. So he switched to another, where he's been ever since.

Zimmerman recalls one member of his group who dominated discussions. After several other members spoke to the man privately about the problem, he resigned from the group. Another time, a consultant running a sole proprietorship decided to leave when he realized he wasn't the right fit.

What you're not likely to get from these organizations is business. Peer groups are not meant for networking. In fact it's discouraged, since members are less likely to expose their vulnerabilities if they think a possible client is in the room.

"The last thing on people's minds is selling," says Kunhardt. "It's the one day of the month when you're not constantly thinking about generating revenue."