Recent advances in neuroscience have allowed researchers from various disciplines - developmental psychology, comparative psychology, and developmental psychopathology - to shed light on the neural systems involved in social engagement behaviours in both children and adults. The Development of Social Engagement presents the latest on the topic from each of these intersecting research areas. Developmental psychologists have long been interested in the constellation of behaviours that constitutes early social engagement in infants and young children. Renewed interest in this topic has been sparked by research applying new and innovative techniques to long-standing questions about the development of face processing, joint attention, language, and early social cognition. These developments have been mirrored by the growth of comparative work concerning the neurobiological correlates and determinants of social engagement behaviours across a range of non-human species. The chapters in this volume bring together work on all of these topics, including questions related to social systems, play, maternal behaviour, and evolutionary concerns. The volume also covers the recent application of rigorous biologically focused research paradigms to the study of atypical social engagement in children, both in terms of disorders such as autism and Williams Syndrome, and in terms of the effects of adverse early rearing environments (e.g., institutionalism). This book presents some of the latest research on social-engagement processes across a variety of disciplines that cover a range of life stages and species. It will provide both student and professional researchers with a taste of current research directions in this rapidly expanding field.