This study examined family characteristics associated with the coparenting behavior of 60 parents with an 11- to 15-month-old infant (30 boys, 30 girls) during a structured triadic play session. Mothers reported on family demographics, social support, and child temperament. Both parents reported on their self-esteem and childrearing beliefs. Fathers displayed more supportive coparenting behavior than mothers. Mothers' intrusive coparenting behavior differed based on the number of children, parent's employment status, and child gender. Social support, parental self-esteem, and child temperament were significant correlates of individual coparenting behavior. Results are discussed in terms of their implications for family theory and family practice.