The Rev. Thomas Worcester is a history professor at College of the Holy Cross in Worcester, Mass., where he teaches a course on the papacy. He is co-editor of The Papacy Since 1500: From Italian Prince to Universal Pastor (2010).

The Association of Statisticians of American Religious Bodies is an organization of statisticians and researchers who collect and publish information about American denominations and faith groups. Every 10 years they publish the Religious Congregations Membership Study, the last of which appeared in 2010.

American Piety in the 21st Century, an extensive survey of beliefs and practices released in 2006, was conducted by the Baylor Institute for Studies of Religion. This study counted one-third of Americans as evangelicals, compared with the Pew study’s one-fourth. It numbered the unaffiliated at 10.8 percent, much lower than the new Pew study and the […]

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.

The BBC maintains a profile on Pope Benedict XVI.

The New York Times has a Times Topics page on Benedict.

Chris Stewart is the California representative for Karate for Christ. He is based in Downey, Calif.