An outline of the public health approach to violence is based on the rigorous requirements of the scientific method. In moving from problem to solution, the public health approach to violence has four key steps: obtaining as much basic knowledge as possible about all the aspects of violence; investigating why violence occurs; exploring ways to prevent violence based on the knowledge obtained; and implementing in a range of settings interventions that appear promising. Following this overview of the public health approach to violence prevention, this chapter defines violence and presents a typology of violence that encompasses self-directed violence, interpersonal violence, and collective violence. An overview of current knowledge about violence addresses estimates of mortality, estimates of nonfatal violence, and the costs of violence. A presentation of an ecological model that explains the causes of violence takes into account the complex interplay of individual, relationship, social, cultural, and environmental factors. Understanding how these factors are related to violence is one of the important steps in the public health approach to preventing violence. In discussing how violence can be prevented, a section of the chapter considers the types of prevention (primary, secondary, and tertiary), multifaceted responses, the documenting of effective responses, balancing public health action, addressing cultural norms, and actions against violence at all levels. The chapter concludes with a discussion of problems for national decision makers. "Boxes" within the chapter provide brief discussions of the public health approach in action in Colombia; the implications of globalization for violence prevention; and a comprehensive approach to preventing violence at work. 3 tables, 3 figures, and 59 references