Puberty is one of the most important life transitions. There is no other period in the life cycle in which there is such significant, rapid, and simultaneous transformation in biology and social and psychological development. Change at puberty is both dramatic and universal, yet there are few researchers who study this important stage in the lifecourse. Indeed the study of the biological and psychosocial changes at puberty is relatively recent. One of the most interesting aspects of puberty is that it marks a significant separation between the genders: physically, psychologically, and socially. This book focuses on the emergence of gender difference and provides an up to date summary of interdisciplinary research in the area with contributions from an international team of leading experts in the field. Topics covered include biological aspects of puberty, body image, aggression, sexual abuse, opposite-sex relationships and the psychopathology of puberty.