We examined associations of maternal and child emotional discourse and child emotion knowledge with children's behavioral competence. Eighty-five upper middle-income, mostly White preschoolers and mothers completed a home-based bookreading task to assess discourse about emotions. Children's anger perception bias and emotion situation knowledge were assessed in a separate interview. Children's prosocial behavior, relational aggression, and physical aggression were observed during a preschool-based triadic play task. Mothers' emotion explanations were correlated with children's emotion situation knowledge and relational aggression. Both mothers' and children's emotion explanations predicted prosocial behavior whereas mothers' use of positive emotional themes was negatively associated with children's anger perception bias. Physical aggression was predicted by mothers' emotion comments, children's anger perception bias, and lack of emotion situation knowledge. Maternal emotion socialization variables were less strongly related to children's behavioral competence after accounting for demographics and child emotional competence. Implications of these findings for future research on emotion socialization are discussed.