V. School-Based Prevention
A. Preschool Programs
The most famous preschool intellectual enrichment program is the Perry project, carried out in Ypsilanti (Michigan) by Lawrence Schweinhart and David Weikart (see Schweinhart et al., 2005). This was essentially a “Head Start” program targeted at disadvantaged African American children. Members of a small sample of 123 children were assigned (approximately at random) to experimental and control groups. The experimental children attended a daily preschool program—backed up by weekly home visits—usually lasting 2 years (covering ages 3–4). The aim of the “plan–do–review” program was to provide intellectual stimulation, to increase thinking and reasoning abilities, and to increase later school achievement. This program had long-term benefits. John Berrueta- Clement (1984) showed that at age 19, members of the experimental group were more likely to be employed, more likely to have graduated from high school, more likely to have received college or vocational training, and less likely to have been arrested. By age 27, the experimental group had accumulated only half as many arrests on average as the controls. Also, they had significantly higher earnings and were more likely to be homeowners. Regarding the women in the experimental group, more were married, and fewer of their children were born to unmarried mothers. The most recent follow-up of this program, evaluating the participants at age 40, found that it continued to make an important difference in their lives. Compared to the control group, those who received the program had significantly fewer lifetime arrests for violent crimes (32% vs. 48%), property crimes (36% vs. 56%), and drug crimes (14% vs. 34%), and they were significantly less likely to be arrested five or more times (36% vs. 55%). Improvements were also recorded in many other important life course outcomes. For example, significantly higher levels of schooling (77% vs. 60% graduating from high school), better records of employment (76% vs. 62%), and higher annual incomes were reported by the program group compared to the controls. Several economic analyses show that the financial benefits of this program outweighed its costs. The Perry project’s own calculation included crime and non-crime benefits, intangible costs to victims, and even projected benefits beyond age 27. This generated the famous cost-benefit ratio of 7 to 1. Most of the benefits (65%) were derived from savings to crime victims. The most recent cost-benefit analysis of participants at age 40 found that the program produced $17 in benefits per $1 of cost.
B. School Programs
The Montreal longitudinal-experimental study combined child skills training and parent training (see McCord & Tremblay, 1992). Tremblay and his colleagues identified disruptive (aggressive or hyperactive) boys at age 6, and randomly allocated over 300 of them to experimental or control conditions. Between ages 7 and 9, the experimental group received training designed to foster social skills and self-control. Coaching, peer modeling, role-playing, and reinforcement contingencies were used in small-group sessions on such topics as “how to help,” “what to do when you are angry,” and “how to react to teasing.” Also, their parents were trained using the parent-management training techniques developed by Gerald Patterson (1982). This prevention program was successful. By age 12, the experimental boys committed less burglary and theft, were less likely to get drunk, and were less likely to be involved in fights than the controls (according to self-reports). Also, the experimental boys had higher school achievement. At every age from 10 to 15, the experimental boys had lower self-reported delinquency scores than the control boys. Interestingly, the differences in antisocial behavior between experimental and control boys increased as the follow-up progressed. A later follow-up showed that fewer experimental boys had a criminal record by age 24 (Boisjoli, Vitaro, Lacourse, Barker, & Tremblay, 2007). One of the most important school-based prevention experiments was carried out in Seattle by Hawkins and his colleagues (Hawkins, Catalano, Kosterman, Abbott, & Hill, 1999). They implemented a multiple-component program combining parent training, teacher training, and child skills training. About 500 first-grade children (aged 6) in 21 classes in 8 schools were randomly assigned to be in experimental or control classes. The children in the experimental classes received special treatment at home and school that was designed to increase their attachment to their parents and their bonding to the school. Also, they were trained in interpersonal cognitive problem solving. Their parents were trained to notice and reinforce socially desirable behavior in a program called “Catch Them Being Good.” Their teachers were trained in classroom management— for example, to provide clear instructions and expectations to children, to reward children for participation in desired behavior, and to teach children prosocial (socially desirable) methods of solving problems. This program had long-term benefits. By the sixth grade (age 12), experimental boys were less likely to have initiated delinquency, while experimental girls were less likely to have initiated drug use. In a later follow-up, Hawkins and his colleagues (Hawkins, Catalano, Kosterman, Abbott, & Hill, 1999) found that, at age 18, the full intervention group (those who received the intervention from Grades 1–6) admitted less violence, less alcohol abuse, and fewer sexual partners than the late intervention group (Grades 5–6 only) or the control group. According to Steve Aos and his colleagues (2001), over $4 were saved for every $1 spent on this program. In Baltimore, Hanno Petras, Sheppard Kellam, and their colleagues (2008) evaluated the “Good Behavior Game” (GBG), which aimed to reduce aggressive and disruptive child behavior through contingent reinforcement of interdependent team behavior. First-grade classrooms and teachers were randomly assigned either to the GBG condition or to a control condition, and the GBG was played repeatedly over 2 years. In trajectory analyses, the researchers found that the GBG decreased aggressive/disruptive behavior (according to teacher reports) up to Grade 7 among the most aggressive boys, and also caused a decrease in antisocial personality disorder at ages 19–21. However, effects on girls and on a second cohort of children were less marked. There have been a number of comprehensive, evidence-based reviews of the effectiveness of school-based programs by Denise Gottfredson, David Wilson, and their colleagues (see Sherman, Farrington, Welsh, & MacKenzie, 2006). Meta-analyses identified four types of school-based programs that were effective in preventing delinquency: school and discipline management, classroom or instructional management, reorganization of grades or classes, and increasing self-control or social competency using cognitive-behavioral instruction methods. Reorganization of grades or classes had the largest average effect size (d = .34), corresponding to a significant 17% reduction in delinquency. After-school programs (e.g., recreation-based, drop-in clubs, dance groups, and tutoring services) are based on the belief that providing prosocial opportunities for young people in the after-school hours can reduce their involvement in delinquent behavior in the community. After-school programs target a range of risk factors for delinquency, including association with delinquent peers. Welsh and Akemi Hoshi identified three high-quality after-school programs with an evaluated impact on delinquency (see Sherman et al., 2006). Each had desirable effects on delinquency, and one program also reported lower rates of drug use for participants compared to controls.
C. Anti-Bullying Programs
School bullying is a risk factor for later offending, and several school-based programs have been effective in reducing bullying. The most famous of these was implemented by Olweus (1993) in Norway. The general principles of the program were to create an environment characterized by adult warmth, interest in children, and involvement with children; to use authoritative child rearing, including warmth, firm guidance, and close supervision, since authoritarian child rearing is related to child bullying; to set firm limits on what is unacceptable bullying; to consistently apply nonphysical sanctions for rule violations; to improve monitoring and surveillance of child behavior, especially on the playground; and to decrease opportunities and rewards for bullying. The Olweus (1993) program aimed to increase awareness and knowledge of teachers, parents, and children about bullying and to dispel myths about it. A 30-page booklet was distributed to all schools in Norway describing what was known about bullying and recommending what steps schools and teachers could take to reduce it. Also, a 25-minute video about bullying was made available to schools. Simultaneously, the schools distributed to all parents a four-page folder containing information and advice about bullying. In addition, anonymous self-report questionnaires about bullying were completed by all children. Each school received feedback information from the questionnaire, about the prevalence of bullies and victims, on a specially arranged school conference day. Also, teachers were encouraged to develop explicit rules about bullying (e.g., do not bully, tell someone when bullying happens, bullying will not be tolerated, try to help victims, try to include children who are being left out) and to discuss bullying in class, using the video and role-playing exercises. Also, teachers were encouraged to improve monitoring and supervision of children, especially on the playground. The effects of this anti-bullying program were evaluated in 42 Bergen schools. Olweus (1993) measured the prevalence of bullying before and after the program using self-report questionnaires completed by the children. Since all schools received the program, there were no control schools. However, Olweus compared children of a certain age (e.g., 13) before the program with different children of the same age after the program. Overall, the program was very successful because bullying decreased by half. A similar program was implemented in 23 schools in Sheffield (U.K.) by Peter Smith and Sonia Sharp (1994). The core program involved establishing a “whole school” anti-bullying policy, raising awareness of bullying, and clearly defining roles and responsibilities of teachers and students so that everyone knew what bullying was and what they should do about it. In addition, there were optional interventions tailored to particular schools: curriculum work (e.g., reading books, watching videos), direct work with students (e.g., assertiveness training for those who were bullied), and playground work (e.g., training lunchtime supervisors). This program was successful in reducing bullying (by 15%) in primary schools, but had relatively small effects (a 5% reduction) in secondary schools. Maria Ttofi and her colleagues (Ttofi, Farrington, & Baldry, 2008) completed a systematic review of the effectiveness of anti-bullying programs in schools. They found 59 high-quality evaluations of 30 different programs. They concluded that, overall, anti-bullying programs were effective. The results showed that bullying and victimization were reduced by about 17% to 23% in experimental schools compared with control schools.
D. Peer Programs
There are few outstanding examples of effective intervention programs for antisocial behavior targeted at peer risk factors. The most hopeful programs involve using high-status conventional peers to teach children ways of resisting peer pressure. Nancy Tobler and her colleagues (Tobler, Lessard, Marshall, Ochshom, & Roona, 1999) found that these were effective in reducing drug use. Also, in a randomized experiment in St. Louis, Ronald Feldman and his colleagues (Feldman, Caplinger, & Wodarski, 1993) showed that placing antisocial adolescents in activity groups dominated by prosocial adolescents led to a reduction in their antisocial behavior (compared with antisocial adolescents placed in antisocial groups). This suggests that the influence of prosocial peers can be harnessed to reduce antisocial behavior. However, putting antisocial peers together can have harmful effects. The most important intervention program whose success seems to be based mainly on reducing peer risk factors is the “Children at Risk” program, which targeted high-risk adolescents (average age, 12) in poor neighborhoods of five cities across the United States. Eligible youths were identified in schools and randomly assigned to experimental or control groups. The program was a comprehensive, community-based prevention strategy targeting risk factors for delinquency, including case management and family counseling, family skills training, tutoring, mentoring, after-school activities, and community policing. The program was different in each neighborhood. The initial results of the program were disappointing, but a 1-year follow-up by Adele Harrell and her colleagues (Harrell, Cavanagh, & Sridharan, 1999) showed that (according to self-reports) youths in the experimental groups were less likely to have committed violent crimes and used or sold drugs. The process evaluation showed that the greatest change was in peer risk factors. Experimental youths associated less often with delinquent peers, felt less peer pressure to engage in delinquency, and had more positive peer support. In contrast, there were few changes in individual, family, or community risk factors, which was possibly linked to the low participation of parents in parent training and of youths in mentoring and tutoring. In other words, there were problems of implementation of the program, linked to the serious and multiple needs and problems of the families. Mentoring programs usually involve nonprofessional adult volunteers spending time with young people at risk for delinquency, dropping out of school, school failure, or other social problems. Welsh and Hoshi (2002) identified seven mentoring programs (of which six were of high quality) that evaluated the impact on delinquency. Since most programs had desirable effects, Welsh and Hoshi concluded that community-based mentoring was a promising approach in preventing delinquency. Similarly, a metaanalysis by Darrick Jolliffe and David Farrington (2008) concluded that mentoring was often effective in reducing reoffending.