Anxious about meeting a key hiring manager? Your job-search jitters may soon intensify when you confront the ultimate stress test: a panel of interviewers.

Group grilling has long been popular among academics, government agencies and nonprofit organizations -- sectors that prefer decisions by a consensus of constituencies. As the job market becomes more competitive for people at every level, this practice is spreading to law firms, management consultancies and high-tech businesses. Employers, who now have the luxury of being picky with candidates, see selection committees as an efficient way to measure applicants' mettle under fire.

Some prospects get no warning before they face several screeners simultaneously. "The first time you have one of these interviews, it will throw you off a little bit," cautions Scott Erker, a senior vice president for Development Dimensions International, a leadership consulting firm in Pittsburgh.

Until five years ago, DDI itself rarely used panel interviews for senior promotions -- but does so about half the time today, Dr. Erker says. He thinks the approach identifies people who work well in a group setting, a critical skill at a business that "demands team collaboration."

He won a promotion in 2004 after passing muster with a panel. "You have multiple sets of eyes and questions coming from different perspectives," he remembers.

With advance notice and extra preparation, you can impress these extra interviewers. It's a good idea to get the names, titles and pecking order of panel members. Do this by asking current and former staffers, and checking the Internet. From your sources, try to get a sense of your session's likely length, number of questions and key issues. You can then assemble a "cheat sheet" of interviewers, draft replies for their possible questions and look relaxed during the meeting.

A man vying for a vice presidency at a financial-services concern last year did a thorough Internet search about its four-member screening committee. He learned one member wrote a newspaper column about martial arts.

He broke the ice at his interview by declaring that he was going to "break a stack of boards over his head in the executive's honor," recalls Sanjay Sathe, a friend and head of RiseSmart, an online job-search service for senior professionals and managers. "It showed the committee that this candidate had done his homework."

The man was named one of two finalists for the job, though he ultimately didn't get it.

An executive recruiter might have offered him additional insights -- as Gwen L. Feder recently did. The partner-placement director for PeterSan Group, a New York legal search firm, counseled a prospect before his joint interview with three law-firm partners she knows well. She described each partner's interaction with colleagues and their expectations of lieutenants. The candidate "made a great impression" and remains in the running, she recalls.

To defuse the stiff formality that tends to come with panel interviews, "show how friendly and important you are," recommends Ruth Haag, a management consultant and CEO of Haag Environmental, a hazardous-waste cleanup business in Sandusky, Ohio. "Shake everybody's hand. Look everybody in the eye. And sell yourself really hard."

You should intersperse colorful anecdotes about your experience with perceptive queries about the vacancy. The tactic "puts you on conversational terms with your interviewers, and also gives you a much-needed breather between the questions thrown your way," Mr. Sathe suggests.

Sit where you can maintain eye contact throughout the room without staring toward a bright window. Otherwise, "you will be squinting and will look angry," notes Marilyn Machlowitz, a New York recruiter.

You also should closely monitor the group dynamics. How screeners introduce themselves, their initial banter and the seating arrangement speak volumes about who wields the most clout.

Body language offers further clues. M.B.A. student Kara Dyer landed a 2006 summer internship in the Chicago office of management consultancy ZS Associates after a panel interview. Three senior officials grilled her about a hypothetical thorny problem for a corporate client.

One manager never smiled, said little and sat "with his arms crossed," she remembers. "I took extra care answering his questions and looked at him a little more" than the rest.

Ms. Dyer was ready for that screener's tough queries. She had practiced case-study presentations before groups of fellow students at MIT's Sloan School of Management. She says the rehearsals made her less nervous during the interview. She joined the Evanston, Ill., firm full time last year.

As Ms. Dyer discovered, "you're not always going to be on the same page with everyone in the room," observes Frederick Shack, executive director of Urban Pathways, a New York nonprofit that offers transition housing for the homeless. But "you can disagree without being offensive."

That's what Mr. Shack did after he donned a suit for his Urban Pathways interview with its board's seven-person search panel.

"You're dressed better than I have ever dressed in my life," complained one member, a retiree attired in jeans and tattered T shirt. "This is how I dress," Mr. Shack replied. Everyone laughed.

Mr. Shack politely differed with another panelist's praise of stability at Urban Pathways, where many staffers enjoyed long tenure.

"I said, 'Not necessarily. It may be there's a real [turnover] need for the organization to grow and move forward.' " The board member "reacted well," according to Mr. Shack.

He became executive director in January 2005 -- and still wears a suit to work every day.

• Email her at Joann.Lublin@wsj.com.