This study looked at the impacts on social-emotional development at school entry of a pediatric primary care intervention called the Video Interaction Project (VIP), promoting positive parenting through reading aloud and play, delivered in two phases: infant through toddler (VIP 0-3) and preschool-age (VIP 3-5). VIP 0-3 resulted in sustained impacts on behavior problems 1.5 years after program completion. VIP 3-5 had additional, independent impacts. The children whose families had participated in the intervention when they were younger were still less likely to manifest those behavior problems — aggression, hyperactivity, difficulty with attention. These results support the use of pediatric primary care to promote reading aloud and play from birth to 5 years, and the potential for such programs to enhance social-emotional development.