Both teachers and students tend to be victimized more violently in the larger cities. Students are the main perpetrators of school violence, except in large cities, where the majority of offenders are intruders. The two types of intruders are predators who are unknown to the school and marginal members of the school community. Most perpetrators are adolescent or young adult males, according to a survey of 26 cities. The same survey showed that blacks were disproportionately represented among offenders. Assaults and robberies of students are twice as great in junior high schools as in senior high schools, indicating that alienated students often drop out of high school. Reducing the age of compulsory enrollment to 15 or lower might improve the educational climate of public schools while at the same time making schools safer places for students and staff. Six tables and seven references are supplied.