The effects of childhood traumatic brain injury (TBI) on social problem-solving were examined in 35 children with severe TBI, 40 children with moderate TBI, and 46 children with orthopedic injuries (OI). The children were recruited prospectively following injuries that occurred between 6 and 12 years of age. They were followed longitudinally, and ranged from 9 to 18 years of age at the time of the current study, which occurred on average 4 years post injury. They were administered a semi-structured interview used in previous research on social problem-solving to assess the developmental level of their responses to hypothetical dilemmas involving social conflict. Children in the severe TBI group defined the social dilemmas and generated alternative strategies to solve those dilemmas at the same developmental level as did children in the OI group. However, they articulated lower-level strategies as the best way to solve the dilemmas and used lower-level reasoning to evaluate the effectiveness of the strategies. After controlling for group membership, race, socioeconomic status, IQ, and age, children's social problem-solving, and particularly the developmental level of their preferred strategies for resolving conflicts, predicted parents ratings of children's social skills, peer relationships, aggressive behavior, and academic performance. The findings indicate that children with severe TBI demonstrate selective, long-term deficits in their social problem-solving skills that may help to account for their poor social and academic outcomes.