The present study examined the relationships between caregivers' self-reported positive and negative emotional expressiveness, observer assessments of children's emotion regulation, and teachers' reports of children's internalizing and externalizing behaviors in a sample of 97 primarily African American and Hispanic Head Start families. Results indicated that higher caregiver negativity and lower child emotion regulation independently predicted more internalizing behavior problems in children. Additionally, children's externalizing behavior problems were negatively predicted by caregivers' self-reports of positive emotional expressiveness. Importantly, results also suggested that caregivers' emotional expressiveness and children's behavioral problems may be non-linearly related, and that child gender may play an important moderating role. These results emphasize the importance of family emotional climate and child emotion regulation in the behavioral development of preschool-age children, and highlight the need for improved theoretical and practical understanding of socioemotional development in diverse populations.