Background: The incidence of psychological, physical, and sexual violence in intimate dating relationships has a significant impact on young people. These issues are of great concern to researchers, educators, and administrators who strive to help youth be happy and healthy. This review focused on prevention and intervention efforts implemented in schools that sought to reduce or prevent incidents of dating violence. Objectives: The main objective of this review was to evaluate and synthesize the efficacy of school-based interventions that sought to reduce or prevent teen dating violence or sexual violence in intimate relationships. Specifically this review evaluated the impact of dating violence prevention programs implemented in middle and high schools on changing attitudes or beliefs supportive of teen dating violence, reducing incidents of dating violence perpetration, or reducing incidents of dating violence victimization. Additionally, this review examined potential substantive or methodological variables (e.g., program characteristics, age, gender, location) that moderated the effect sizes. Search Strategy: An extensive search strategy was used to identify qualifying studies. Various electronic bibliographic databases were searched in July 2013, along with government databases, grey literature databases, and citations in other reviews. In addition, we searched the reference lists of primary studies, hand searched relevant journals, and searched the Internet using Google and Google Scholar. We also contacted researchers who have published extensively in the area of teen dating violence and researchers who have received grants to implement teen dating violence prevention programs to identify studies in press or in preparation. Neither language nor date restrictions were applied to the searches. Selection Criteria: Studies were required to meet several criteria to be eligible for inclusion. Studies must: (1) have a well-defined control group. (2) include a school-based intervention, implemented with students between 4th and 12th grade. (3) have a primary goal of reducing or preventing teen dating violence or sexual violence in intimate relationships. (4) measure the impact of the program on either attitude change, frequency of intimate partner violence perpetration or victimization, teen dating violence knowledge, or on the ability to recognize both safe and unhealthy behaviors in intimate partner disputes. Studies were excluded if they measured the above outcomes as secondary outcomes. Studies that utilized community centers or other locations outside the brick-and-mortar schools were also excluded. Data Collection and Analysis: The literature search yielded a total of 1,608 references, of which 90 were deemed potentially relevant and retrieved for additional screening. Of these 90 studies, 23 were included in the study after a full review. Meta-analysis was used to examine the effects of school-based programs versus a control group on increasing knowledge of teen dating violence, changing attitudes or beliefs supportive of teen dating violence, reducing incidents of dating violence perpetration, and reducing incidents of dating violence victimization. A three-level meta-analytic model was utilized to synthesize the effect sizes. Results: This systematic review found that prevention programs do have an impact on teen dating violence knowledge and attitudes. At post-test, students in the intervention conditions increased their knowledge and endorsed attitudes that were less accepting of violence in relationships. In addition, at post-test, prevention students were less accepting of rape myths and reported an increased awareness of appropriate approaches to conflict resolution. The positive results for teen dating violence knowledge and attitudes were supported at follow-up. However the results for dating violence perpetration and victimization were less encouraging. Although only a limited number of studies focused on these outcomes, the results indicated that prevention programs are not impacting these behaviors to a great extent. Moderation analysis did not find any significant variables that impacted the effect sizes. Authors' Conclusions: The results of this review are tentatively encouraging, but also highlight the need for modifications to programs in order to support schools using time and resources to implement teen dating violence prevention programs. Specifically, programs will need to be refined so that they support behavior change, with future research focusing on program development that explicitly seeks to incorporate skill-building components in an effort to impart behavior change. Additionally, future research should explore the role of bystanders more explicitly, examining how prevention programs may shift the peer culture to be less tolerant of dating violence. [This systematic review was funded by the Education Coordinating Group of the Campbell Collaboration.]