This cohort study examined the neurobehavioral, academic, and "real world" consequences of mild, moderate, and severe traumatic brain injury in children at 3 years following the resolution of posttraumatic amnesia. Seventy-two children, aged 6 to 15 years at time of injury, were individually matched with controls on the basis of age, gender, school grade, and the classroom teacher's assessment of premorbid academic achievement and behavior. Both groups were assessed using the same standardized neuropsychological test battery and parent and teacher report measures as were used initially and at 1-year follow-up covering 10 cognitive, behavioral, and functional domains. The performance of both moderately and severely injured children was worse than their controls on 40 out of 53 variables. The association of outcome variables with injury severity was validated using school achievement tests and grades. Analyses of the impact of preinjury variables and study dropouts on outcome showed no threat to the validity of study findings. These results provide strong validation for the persisting and comprehensive nature of neuropsychological deficits in children and adolescents with moderate and severe traumatic brain injury.