Joseph Chinnici is a Franciscan friar and professor of history at the Franciscan School of Theology, which is affiliated with the University of San Diego. He is the author of When Values Collide: The Catholic Church, Sexual Abuse and the Challenges of Leadership.

William Swatos Jr. is executive director of the Religious Research Association, a group of academic and religious professionals that applies scientific research methods to the study of religion. It is a project of the Hartford Seminary. He is located in Illinois.

John Zogby is president of Zogby International, a polling organization based in Utica, N.Y., that frequently includes questions about religion and adherence in its polls.

Tom Smith is a senior fellow and director of the General Social Survey at the National Opinion Research Center at the University of Chicago. He is at work on a study of religious change, including how people think about God. He served as a consultant to the Religious Landscape study and is an expert on Catholics and Protestants.

Lawrence Cunningham is a theology professor at the University of Notre Dame. He wrote the entry on angels in the Harper Collins Dictionary of Religion. He can also discuss the Catholic data in the study.

Duane Garrett is a professor of Old Testament interpretation at Southern Baptist Theological Seminary in Louisville, Ky. He wrote Angels and the New Spirituality.

Michael Rogness is a professor of preaching at Luther Seminary in St. Paul, Minn., who has written about popular fascination with angels.

Vinita Hampton Wright is a Chicago-based novelist and religion editor who wrote A Catalogue of Angels: The Heavenly, the Fallen and the Holy Ones Among Us (2006), about angels in the three Abrahamic traditions.

Ross Stolzenberg is a sociology professor at the University of Chicago. He has written about Jewish concepts of the afterlife.