The purpose of this chapter is threefold. First, the chapter summarizes what is known about the prevalence of violence and weapons in U.S. schools. Second, the chapter examines theories that bear on school violence and the empirical evidence linked to those theories. Third, the chapter looks at attempts to prevent school violence and, consequently, the suffering school violence causes. (Contains 6 tables.) [Schonfeld, I.S. (2006). School Violence (pp. 169-229). In: E.K. Kelloway, J. Barling, & J.J. Hurrell (eds). Handbook of Workplace Violence. Thousand Oaks, CA: Sage Publications.]