Injuries are a disease process that costs billions of dollars every year in direct and indirect costs. Despite recent emphasis on prehospital systems and trauma care, prevention of injuries remains an area underutilized by physicians. As a disease process, injuries are amenable to evaluation with epidemiologic tools and subject to prevention by modifying the transmission of energy to human beings. This may occur by either active or passive means of intervention. Physician leadership in the prevention of injuries is important, yet few physicians have training in injury control. The concepts of injury control are presented by defining the components that create injury and by examining the factors that affect each component. Strategies for identifying countermeasures are described and the merits of each of the applications of countermeasures are discussed. The physician must understand these basic concepts of injury control to an effective leader in developing strategies that mitigate injury in the community.