This chapter begins by presenting a figure detailing the variety of school-related precursors to delinquency that have been identified by crime prevention research. Discussing school-based crime prevention programs, the authors describe a variety of prevention programming focusing on altering school or classroom environments and changing the behaviors, knowledge, skills, attitudes, and/or beliefs of individual students. After detailing the methods used to assess the various school-based crime prevention programs, the authors summarize evidence from 178 empirical studies that address what works and what does not work in terms of school-based crime prevention programming. The authors found that changing school and classroom environments by building a school’s capacity to manage itself and to manage discipline, by establishing norms and expectations for behavior, by managing and reorganizing grades and classes, and by changing the ways that students are instructed positively impact students leading to lower levels of criminal activity. Discussing school-instructional programs that focus on social competency skills development and using cognitive-behavioral or behavioral methods, the authors found that such programs led to violence prevention within the classroom as well as increased student desire to participate in recreational, community service enrichment, and leisure activities. The authors maintain that additional research is needed to better understand the full potential of such school-based intervention strategies. Tables, references