Blunt and penetrating force injuries to the brain constitute an enormous public health problem. If a child or young adult survives a moderate or severe brain injury, there is a strong likelihood of a lifetime of physical and mental impairment as well as tremendous economic and social impact on the family. The magnitude of this problem has only been recently appreciated, yet many questions on the causes and short- or long-term outcomes remain unanswered. One conclusion is clear: prevention is the best solution, but information on the nature of the brain injury, exposure factors, and effectiveness of countermeasures is incomplete. We sought to summarize certain basic epidemiological data on brain injuries in infants, children, adolescents, and young adults as well as findings on incidence of brain injury and current data on demographics and risk factors. We also estimated disability and person-years of life lost from brain injuries and highlight the value of helmets as a countermeasure for several exposures to head injury.