What Works to Prevent Violence in Schools: The Behavioral Approach

Bullying can be prevented. For ministries of education, the central question is how—especially when faced with numerous options that yield varying results. The Inter-American Development Bank (IDB) synthesized 88 impact evaluations from around the world, and this new evidence helps answer a crucial question: Can school programs successfully curb aggression and bullying, and offer viable solutions for Latin America and the Caribbean?

This post is part of Schools that Care, an IDB blog series that brings together the evidence on what works to prevent violence through schools. Here, we summarize the most effective behavioral strategies and highlight key research gaps that still need to be addressed in the region.

What Is Behavioral Violence Prevention?

Behavioral violence prevention (BVP) encompasses school-based initiatives designed to foster behavioral change. It broadly comprises two core approaches:

1. Cognitive behavioral therapy (CBT): Focuses on cognitive reframing and emotional self-regulation.
2. Socioemotional and behavioral development programs: Build socioemotional skills and promote positive social behavior.

The full results are available in the IDB’s Information Center for the Improvement of Learning (CIMA) Evidence Brief “What Works in Behavioral School-Based Violence Prevention?” Effects are expressed in standard deviations (SD), a standardized measure showing the degree of change relative to typical student-level variation, allowing direct comparisons across different interventions. To interpret these figures, the brief applies the benchmarks proposed by Matthew Kraft (2020), which provide context for assessing educationally meaningful impacts.

Which Anti-Bullying Programs Work Best?

The evidence highlights four key characteristics of successful programs:

1. Embedded into the core curriculum and daily schedule. According to the systematic review of evidence, integrating these activities directly into the regular curriculum proves to be the most effective approach. Interventions delivered outside class time, or as a standalone subject achieve moderately smaller effects. Programs that cross-cut prevention across subjects during regular school hours yield the largest average effect: 0.41 SD.
2. Focused on emotional regulation. Strategies that develop self-regulation skills prove especially effective in school settings. Programs combining socioemotional and behavioral development are the most widely evaluated, demonstrating consistent effectiveness and broad applicability across contexts. Among all approaches, Cognitive Behavioral Therapy (CBT) shows the strongest impact on violence-related behaviors (0.94 SD).
3. Delivered face to face. In-person programs yield strong, lasting effects (0.40 SD), driven by direct interpersonal interaction and peer modeling.
4. Effective across primary and secondary levels. Positive impacts remain consistent throughout all stages of compulsory education.

In 2025, the IDB advocated for integrating socioemotional development into national curricula as a cross-cutting priority. This systematic review further reinforces the rationale for behavioral violence prevention.

What Do Violence Prevention Programs Change for Students?

These programs significantly curb bullying, achieving an average effect size of 0.45 SD. Physical and verbal aggression also decline, though more modestly, which suggests these behaviors may be harder to change.

These programs also reshape how students perceive violence. They reduce their acceptance of violence by challenging the underlying beliefs and social norms that legitimize it (0.27 SD) while enhancing their ability to recognize its different forms (0.37 SD).

There are significant mental and emotional health benefits as well, even if they are not the primary objective of these interventions: Anger levels decrease (0.37 SD), and anxiety and stress also decline (0.27 SD).
 

Does It Work in Latin America and the Caribbean?

The evidence indicates that these programs have moderate effects in Latin America and the Caribbean. In the region, the average effect is 0.27 SD, the same as in high-income countries. This falls within the range considered educationally meaningful, which means these programs can generate policy-relevant improvements across diverse settings.

What Do We Still Need to Know about Bullying Prevention?

The evidence on reducing aggression and bullying is robust, but it leaves some important questions open for the region. The first is where the evidence comes from: most studies were conducted in a small group of high-income countries, led by the United States.
 

Latin America is making a growing contribution to this evidence base, with studies from Brazil, Chile, Colombia, and Mexico. However, significant knowledge gaps remain in Central America and the Caribbean. For the region, this presents a key opportunity to build localized evidence on what works in its schools.

Additionally, evidence regarding virtual programs remains sparse. The only available estimate for a fully online intervention shows almost no effect (0.01 SD), while hybrid formats achieve only modest impacts (0.10 SD). In other words, the success of these interventions likely hinges on interpersonal dynamics that are hard to replicate online.

Substantial evidence gaps also remain regarding whole-school prevention models and violence outside the school context. Furthermore, a study by David Evans, Gabriela Smarrelli, and Yi Ning Wong points to a lack of evidence regarding the impact of law enforcement and improved institutional responses to violence.

What Governments Can Prioritize

For education policymakers, the following recommendations are key to driving impactful reform:

1. Integrate prevention into the formal curriculum, within regular school hours, which is the strategy with the largest effect. Repeated exposure and ongoing reinforcement across subjects can deliver compounding benefits.
2. Prioritize in-person delivery. Hybrid formats are only effective when they preserve meaningful opportunities for face-to-face interaction.
3. Support comprehensive programs with strong implementation capacity, especially those incorporating multi-tiered components.
4. Rigorously evaluate interventions across diverse regional contexts, as current data limitations constrain the generalizability of findings. 

More Evidence on What Works

The CIMA Evidence Brief is part of the “What Works in Education” series, an evidence notes series which presents findings from a systematic review of the evidence on what works across a range of education topics. Read the full results here, and explore the interactive evidence maps. Visit CIMA for more evidence briefs on what works in education.