A study investigated the relationship among four possible mechanisms for children's socialization of emotion: (1) mothers are essentially modeling the expression of emotion; (2) mothers' emotions serve a coaching function; (3) the affective environment to which a child is exposed may impact general social-emotional competence; and (4) mothers' reactions to childrens' emotions may form an important foundation of children's social-emotional competence. Emotions of 48 mothers and children were assessed. Subjects were 23 boys and 25 girls, with a mean age of 44 months. The first measure was nonverbal, and the second, which was used a year after the first, was verbal. Reactions to peers' negative emotions were observed in preschool, and social competence in preschool was assessed by teachers and peers. Findings revealed that less angry mothers had children who were more balanced. Children who demonstrated greater comprehension of emotional situations were older, with less angry mothers. Children who experienced more happiness and tenderness at the time of the first measure found it easier to verbalize their emotions a year later. Children who were less neutral toward mothers and had less apprehensive mothers coped better with negative peer reactions. Socialization of emotion variables predicted most general indices of social-emotional development. (SAK)