Although student crime victimization has fallen in recent years, school bullying has increased. Bullying can contribute to an environment of fear and intimidation in schools (Ericson, 2001). In 2003,7% of students reported being bullied at school in the previous 6 months (U.S. Department of Education, 2004). The percentage of students who reported being bullied increased between 1999 and 2001, although no increase was detected between 2001 and 2003 (ISCS, 2004). School violence can make students fearful of the education environment and negatively affect their ability to learn. In response to this continuing threat of school violence and because No Child Left Behind requires a local education action plan that uses "evidence-based" programs, many school districts have adopted science- or evidence-based programs to reduce the violence among their students. Although there may well be many important and valuable secondary effects from school-based violence prevention programming, it is worth asking how effective these programs are in reducing the violent and antisocial behaviors they are funded to prevent. Although a seemingly simple question to ask, estimating the effectiveness of school-based violence prevention programs is not straightforward. In the current meta-analytic study, we describe the overall effectiveness of school-based violence prevention programs in reducing various violent and other antisocial behaviors. From this investigation, several observations emerged. The first and perhaps most profound observation concerned the depth of knowledge available on the effectiveness of these programs for reducing violent behavior. Of the 261 reports, 50 used the term violence in their title. Once the data were coded, however, only five independent study samples presented data on the effectiveness of these programs at preventing or reducing interpersonal physical violence. Although these programs are generally, and in some cases remarkably, effective, knowing that they are worth implementing cannot be determined from the evidence summarized because elements of worth are not generally reported in the research that is included in this meta-analysis. As a final caution, although this summary provides an accurate representation of the impact of these programs on violent and antisocial behaviors, the absolute effect of these programs on the incidence these behaviors may, in fact, be higher or lower than the evidence summarized suggests.