While several recent popular books address the topic of girls' meanness to one another, this volume offers the first balanced, scholarly analysis of scientific knowledge in this area. Integrating current research on emotion regulation, gender, and peer relations, the book examines how girls are socialized to experience and express anger and aggression from infancy through adolescence. Considered are the developmental functions of such behaviors as gossip, friendship manipulation, and social exclusion; consequences for both victims and perpetrators; and approaches to intervention and prevention. Presenting innovative research models and methods, this is an accessible and much-needed synthesis for researchers, professionals, and students.