Peter Gray was a full-time professor of psychology at Boston College for 30 years, where he served his department at various times as Department Chair, Undergraduate Program Director, and Graduate Program Director. He has published research in biological, evolutionary, cultural, developmental and educational psychology; published articles on innovative teaching methods; taught more than 20 different undergraduate courses, including, most regularly, introductory psychology; helped develop a university-wide program to improve students' study and learning skills; and developed a program of research practicum courses. He is now retired from regular teaching, but maintains a position as Research Professor at Boston College. Most of his current research and writing has to do with the value of play, especially free age-mixed play, in children's development. He is author of a popular weekly blog entitled Freedom to Learn: The Roles of Play and Curiosity as Foundations for Learning.

Before joining Boston College, Peter Gray studied psychology as an undergraduate at Columbia University and earned a Ph.D. in biological sciences at Rockefeller University. He earned his way through college by coaching basketball and working with youth groups in New York City. As a graduate student he directed a summer biology program for talented high school students from impoverished neighborhoods. His avocations today include long distance bicycling, kayaking, and backwoods skiing.

David F. Bjorklund, Ph.D., is a Professor of Psychology at Florida Atlantic University, where he has taught graduate and undergraduate courses in developmental and evolutionary psychology since 1976. He received a BA degree in Psychology from the University of Massachusetts in 1971, an MA degree in Psychology from the University of Dayton in 1973, and a Ph.D. degree in Developmental Psychology from the University of North Carolina at Chapel Hill in 1976. He has received numerous teaching and research awards from Florida Atlantic University, and is the recipient of an Alexander von Humboldt Research Award. He served as Associate Editor of Child Development (1997-2001) and is currently serving as Editor of the Journal of Experimental Child Psychology. He has served on the editorial boards of numerous journals and also served as a contributing editor to Parents Magazine. He has published more than 170 scholarly articles on various topics relating to child development and evolutionary psychology and has received financial support for his research from the National Science Foundation, the Spencer Foundation, and the German Research Foundation. His other books include Children's Thinking: Cognitive Development and Individual Differences, now in its fifth edition; Why Youth is Not Wasted on the Young; Looking at Children: An Introduction to Child Development (with Barbara Bjorklund); Parents Book of Discipline (with Barbara Bjorklund); Applied Child Study (with Anthony Pellegrini); The Origins of Human Nature: Evolutionary Developmental Psychology (with Anthony Pellegrini); Children's Strategies: Contemporary Views of Cognitive Development; False-Memory Creation in Children and Adults: Theory, Research, and Implications; and Origins of the Social Mind: Evolutionary Psychology and Child Development (edited with Bruce Ellis). His current research interests include children’s cognitive development and evolutionary developmental psychology. He lives in Jupiter, Florida, with his wife Barbara, and enjoys traveling, cooking, playing basketball, and kayaking.