• The behavior of 10394 British children was related prospectively to their injury history between ages 5 and 10 years, obtained from parents. Aggressive and overactive behaviors at age 5 years were measured by subscales of the Rutter Child Behavior Questionnaire completed by the parents. Multivariate techniques were used to assess the association between behavior and injuries while controlling for social, demographic, and psychological characteristics. Boys' behavior at age 5 years was more strongly predictive of injuries in the subsequent five years than was girls' behavior. The odds of experiencing injuries resulting in hospitalization in boys with high aggression scores was 2.4 times that of boys with low aggression scores. The identification of high-risk children provides the foundation for understanding the behavioral mechanisms that contribute to injuries and for developing preventive strategies tailored to the needs of these children.