Martha Putallaz, PhD, is Professor of Psychology at Duke University, where she joined the faculty in 1983. Dr. Putallaz is a long-standing researcher in the field of children's social development and peer relationships. Most recently, she has been Principal Investigator of a comprehensive study of aggression and social rejection among middle childhood girls, funded by the National Institute of Mental Health. She is also a codirector of the Carolina Consortium on Human Development and the executive director of Duke's Talent Identification Program. Karen L. Bierman, PhD, is Director of the C...