Research Findings: We examined relations of effortful control with parent emotion socialization practices and child social behavior using a person-centered approach in children ages 18 months to 5 years. A total of 76 parents (66 mothers, 10 fathers) completed questionnaires at screening and 6-month follow-up. There were no age differences in change in effortful control. K-means cluster analysis identified 2 clusters for parent emotion socialization: low-involvement parents (lower levels on emotion coaching/dismissing and positive/negative expressivity) and high-involvement parents (higher levels on all such practices). Parent socialization profile was indirectly associated with children's positive social behaviors through children's change in effortful control. These associations did not extend to aggressive behavior. Children with parents who actively engage in a variety of emotion socialization practices may increase more in regulatory capacities and engage in more positive social behavior. Practice or Policy: The present study suggests the importance of using a variety of socialization strategies with young children to foster adaptive regulatory and social behaviors.