Gerhard Lenski is Alumni Distinguished Professor of Sociology at the University of North Carolina at Chapel Hill. He is also the author of The Religious Factor and Power and Privilege. He is a fellow of the American Academy of Arts and Sciences,a former Guggenheim Fellow, and an IREX Senior Faculty Exchange Fellow. Patrick Nolan is Professor and Chair of Sociology at the University of South Carolina at Columbia. He received his Ph.D. degree in sociology from Temple University, where he was a NDEA Title IV Fellow. He has been teaching introductory sociology for more than two decades, and he has published a number of papers on macrosociology and societal evolution written singly and in collaboration with Gerhard Lenski. He was coauthor of the sixth edition of Human Societies, and author of its Instructor's Manual and Student Study Guide. Jean Lenski (1928-1994) was a writer and poet who coauthored the six previous editions of Human Societies, collaborated in the writing of Power and Privilege, and is the author of a recently published volume of poetry, Genesis: The Poetry of Jean Lenski.