Gary McIntosh is professor of Christian ministry and leadership at Biola University in La Mirada, Calif. He is also a consultant and the author of 13 books on church growth.

Carson Mencken is a sociology professor at Baylor University in Waco, Texas, and one of the authors of the Baylor Religion Survey released in 2008. He can discuss its findings on megachurches.

Kevin Dougherty is an associate professor of sociology at Baylor University in Waco, Texas. His research focuses on the sociology of religious congregations, including racial diversity in churches.

Marc von der Ruhr is an associate professor of economics at St. Norbert College in De Pere, Wis. He is interested in the economics of religion, and megachurches are the focus of several of his research projects.

Joseph P. Daniels is an economics professor at Marquette University in Milwaukee. He co-authored a paper that presented an economic model of “religious investment” to explain how seeker-oriented megachurches attract and keep members.

Bill Day is a professor at New Orleans Baptist Theological Seminary and associate director of its Leavell Center for Evangelism and Church Health. His areas of specialization include evangelism and church growth.

Lizette Beard is project manager for LifeWay Research, where she has coordinated projects about megachurches and multisite churches. LifeWay is affiliated with the Southern Baptist Convention and is based in Nashville, Tenn.

Sandra Barnes is a professor of human and organizational development at Vanderbilt University in Nashville, Tenn., whose research interests include the sociology of religion. She is the author of The Black Mega Church: Framing and Addressing HIV/AIDS and Poverty in the Age of Health and Wealth Theology.

Os Guinness is an author and social critic who lives in McLean, Va. His books include Dining With the Devil: The Megachurch Movement Flirts With Modernity. He is a senior fellow at the EastWest Institute in New York City.