INTRODUCTION Schools offer prevention specialists regular access to students throughout their developmental years and may offer the only consistent access to the most crime-prone youths during their early school years (Gottfredson, 1998). A school that implements and maintains an effective program may improve overall school climate and in so doing have a positive effect on youth behavior both during and after school hours. The lack of positive feelings for and identification with one's school have been shown to be directly related to juvenile delinquency. For example, in a study of the predictors of in-school substance use among high school students, Voelkl and Frone (2000) found that students' lack of identification with school was significantly related to both in-school alcohol and marijuana use. According to Gottfredson (1998), programs aimed at clarifying and communicating norms about behaviors are effective ways to reduce crime, delinquency, and substance abuse. Prevention programs directed at positively altering the school and classroom environment seek to reduce or eliminate problem behaviors by changing the overall context in which they occur. These strategies may include interventions to 1) change the decision-making processes or authority structures (building school capacity), 2) redefine norms for behavior and signal appropriate behavior through the use of rules (setting norms for behavior), 3) provide greater flexibility in instruction (classroom organization), 4) implement the use of rewards and punishments and the reduction of down time (classroom management), and 5) reorganize classes or grades to create smaller units, continuing interaction, and different mixes of students. Programs that have the capacity to build students' attachment to their school are often highlighted as models for prevention. THEORETICAL CONTEXT Prevention programs aimed at improving the school or classroom environment are closely linked to social organization theory, because they have a holistic approach, working from the premise that all aspects of school life can affect violence and substance abuse (Sherman et al., 1998). Gottfredson (1998) identifies such programs, which are "aimed at clarifying and communicating norms and behaviors," as effective prevention approaches. Several of these practices that were shown effective (in at least one study, or include components that have been found successful) were directly related to school or classroom environment strategies: