A landmark volume in the scientific study of identity formation and youth development, this fully revised second edition synthesizes sociological and psychological approaches to the study of identity.It illuminates the challenges and opportunities that contemporary young people face as they attempt to form identities in societies undergoing transition. The book introduces simplified identity formation theory, which helps newcomers connect the dots across a broad and promising area of study.Part I places the “identity question” in historical and cultural context, providing a multidimensional framework for studying the developmental dynamics of identity formation.Part II examines the development of perspective taking and moral reasoning, exploring their relationship to ethics and agency in identity formation.Part III investigates scientific evidence concerning identity formation in various societal contexts, implications for understanding youth mental health problems, and the most promising treatments, programs, and practices for addressing the identity issues young people face today. This book is an essential text for advanced undergraduate and graduate students studying self and identity development within developmental psychology, social psychology, clinical psychology, and sociology.Educators and practitioners in child welfare, mental health services, social work, youth and community work, and counseling will also benefit from its introductory and jargon-free nature.