*Authoritative reference, updated and expanded; 55% new material includes new topics, such as neuroscience, social media, social inequality, and novel interventions. *Cutting-edge coverage of perennial topics, including aggression, withdrawal, psychopathology, friendships, romance, and the influence of families and schools. *Interdisciplinary contributors include experts from developmental and clinical psychology, family studies, and sociology. *Competing titles are dated and less comprehensive.