Preschool children from economically disadvantaged families often experience difficulties in developing prosocial behavior. Risk associated with depressive symptomatology in caregivers (parents and guardians) may further compound these difficulties. The overall objective of the present study was to examine the compensatory effect of Head Start classroom environments on the development of prosocial behavior among children with caregivers high in depressive symptomatology. We initially examined the association between caregiver depressive symptoms and children's starting levels of prosocial behavior and then tested classroom emotional support as a moderator of the relation between caregivers' depressive symptoms and children's prosocial behavior development during the school year. The sample of 194 Head Start preschoolers in 28 classrooms was part of a larger study designed to test the effects of an emotion-based prevention program. As expected, caregivers' levels of depressive symptoms predicted lower starting levels of prosocial behavior. However, classroom emotional support promoted improvements in prosocial behavior for the children of the caregivers high in depressive symptomatology. The implications of these findings for the development of preventive interventions are discussed. (Contains 1 figure and 2 tables.)