Injuries are the leading cause of mortality among children.1 To develop effective injury prevention programs, more information is needed regarding the incidence, severity, and etiology of injuries sustained by children of different age groups and in different settings. Childhood injury research has focused primarily on severe injuries and the physical environmental hazards that contribute to those injuries.2-4 Although the incidence of severe injuries is critically important from the perspective of morbidity and mortality, these injuries are relatively rare and consequently difficult to study. Scheidt5 has suggested that it may be useful to determine whether there are reliable markers of risk for severe injuries that are based on more frequently occurring events or easily observable indicators. Minor injuries, the most common type of injury that occurs in child-care settings,6-8 may be a marker of risk for severe injuries; however, previous research has not investigated the relationship between minor and severe injuries. Childhood injury research has also typically focused on a single category of etiologic factors, generally either environmental factors such as climbing equipment and impact surfaces,2,9 or child factors such as aggression, overactivity, and personal characteristics.10-11 The relative importance of different etiologic factors and the joint contributions of child-related and environmental factors have not been thoroughly examined. Research on childhood injuries indicates that a small subgroup of children, usually 15% to 20% of a sample, sustain the majority of injuries in any given setting.6,8,10,12 This phenomenon may be the result of chance or characteristics of the subgroup that may differ from those of other children.