This research in behavioral pediatrics examines, first, contributions of developmental and individual-differences factors to children's understanding of routine medical care and of strategies for coping with distressing medical experiences and, second, child development under cocaine exposure. The research on children's understanding of and responses to medical care integrates the adult stress and coping literature, research on changes in children's cognitive capabilities as they mature, literature pertaining to preparing children for hospitalization, and recent theoretical work regarding the effects of routine pediatric health problems and treatment on child development. The research on development under cocaine exposure addresses issues central to understanding ongoing transactions between biological factors and environmental conditions as they relate to various developmental outcomes. A third focus of collaborative behavioral pediatrics research is on factors related to the incidence of injuries in young children in full-time child care.