Part1: Foundations Underlying Emotion Socialization. Chapter 1: Key theories in emotion socialization of youth. Chapter 2: Biological underpinnings on emotion socialization in the developing brain. Chapter 3: Thinking and feeling: Cognitive foundations of emotional development. Chapter 4: Developmental changes in youth's close peer relationships and their associations with emotion. Chapter 5: Cultural contexts of emotion socialization. Chapter 6: Racial-ethnic diversity in youth's emotion socialization. Chapter 7: Assessment of caregiver and friend emotion socialization. Part2: Emotion Socialization in the Family. Chapter 8: Emotion socialization of children in family contexts. Chapter 9: Emotion socialization of adolescents in family contexts. Chapter 10: Bidirectional relations between caregiver emotion socialization and youth psychopathology and neurodiversity. Chapter 11: Emotion socialization of children and adolescents in high-risk caregiving contexts. Part3: Emotion Socialization in Close Peer Relationships. Chapter 12: Emotion socialization in elementary-school-age children's friendships and peer groups. Chapter 13: How emotions are socialized within friendships during adolescence. Chapter 14: Emotion socialization in adolescent romantic relationships. Chapter 15: Social processes related to emotion socialization in adolescence. Chapter 16: Socialization of emotion regulation in digital contexts. Part4: Applications of Emotion Socialization Knowledge. Chapter 17: Interventions focusing on parent emotion socialization. Chapter 18: Interventions focusing on emotion socialization in neurodivergent youth. Chapter 19: Emotion socialization interventions for families affected by stressful and traumatic events.