This project is a continuation of an earlier study. The earlier study was the largest, community-based investigation of the neurobehavioral sequelae of mild closed head injuries (CHI) in children and adolescents. Using a case-finding system of 25 emergency rooms, the investigators identified groups of children with mild CHI (n=137) and mild injuries not involving the brain (n=132). A non-injury control group (n=114) was recruited through community schools. Evaluations were conducted one, six and twelve months post-injury to assess key neuropsychological, behavioral and academic outcomes. This case-finding system yielded a sample of children with very mild CHI. For example, 95 percent of the children with CHI had been unconscious for less than 10 minutes. The results indicate that children with this mild a CHI did not show functional morbidity relative to the other injury and non-injury groups. Left still unanswered is the question of the minimal acute CHI severity necessary to produce impairment in children and adolescents. The proposed project has been designed to address this issue by sampling a more severe range of CHI injury severity than the prior study, including a range of severity known from prior research to produce significant functional morbidity. The proposed study will capitalize on the large non-injury group and the normative data collected in the earlier study by using the identical outcome measures used in the earlier study. The proposed study will use a new case-finding system consisting of three neurosurgery centers included in the newly funded UCLA Brain Injury Research Center. Children and adolescents with Glasgow Coma scores 6-15 (with a minimal interruption of consciousness greater than one hour) will be assessed immediately prior to hospital discharge on a brief neuropsychological battery and as in the prior study one, six and twelve months post injury. A major objective of the proposed study is to determine the minimal threshold of acute CHI severity necessary to produce significant neuropsychological impairments and/or school and behavior problems during the one year post injury in children and adolescents who are hospitalized within 24 hours of sustaining a CHI. The investigators will determine if neuropsychological functioning at hospital discharge and/or at one month post-injury predicts which children show new school and behavior problems during the one year post injury. The investigators will test the hypothesis that certain factors (e.g., prior history of central nervous system impairment, presence of CT scan abnormalities, the age of the child when injured, the sex of the child and the presence of multiple traumas) modify the minimal threshold of acute CHI severity that is necessary to produce functional morbidity.