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Violence Prevention: School-based Anti-bullying Interventions


What the CPSTF Found

About The Systematic Review

CPSTF uses recently published systematic reviews to conduct accelerated assessments of interventions that could provide program planners and decision-makers with additional, effective options. The following published review was selected and evaluated by a team of specialists in systematic review methods, and in research, practice, and policy related to school-based violence prevention interventions.

Fraguas D, Diaz-Caneja CM, Ayora M, Duran-Cutilla M, Abregu-Crespo R, et al. Assessment of school anti-bullying interventions: a meta-analysis of randomized clinical trials. JAMA Pediatrics 2021;175(1):44-55.

The published review included 69 studies overall (search period through February 2020). The CPSTF abstracted supplemental information about study, intervention, and population characteristics for the subset of 19 studies conducted in the United States or Canada.

The CPSTF finding is based on results from the published review, additional information from the subset of studies from the United States and Canada, and expert input from team members and CPSTF.


Bullying is a form of youth violence and an adverse childhood experience (Gladden et al. 2014). Bullying is a common behavioral problem that is prevalent at all school levels (Diliberti et al. 2019). Bullying has been associated with physical and mental health problems for perpetrators (David-Ferdon et al. 2016), victims (Singham et al. 2017), and youth who witness bullying (Doumas et al. 2020). Exposure to bullying is also related to adverse effects on academic achievement, employment status, and social relationships (Wolke et al. 2015).

Schools can have an important role in bullying prevention efforts, which may contribute to a safe and supportive environment for learning. School-based interventions may complement family- and community-based prevention efforts to reduce bullying both inside and outside of school (David-Ferdon et al. 2016; Hahn et al. 2007).

Summary of Results

Detailed results from the systematic review are available in the CPSTF Finding and Rationale Statement.

The published systematic review and meta-analyses included 69 studies.

  • Students reported small reductions in both bullying perpetration (35 studies) and victimization (32 studies).
  • Student assessments of mental symptoms including anxiety, depression, and well-being improved (20 studies).
  • Studies addressing cyberbullying found small reductions in combined measures of cyberbullying perpetration and victimization (5 studies).

Summary of Economic Evidence

A systematic review of economic evidence has not been conducted.


Based on the results from the review, findings should be applicable to primary and middle school students in the United States.

Evidence Gaps

CPSTF identified several areas that have limited information. Additional research and evaluation could help answer the following questions and fill remaining gaps in the evidence base. (What are evidence gaps?)

  • Which activities and combinations increase intervention effectiveness?
  • How effective are interventions for groups at increased risk for bullying and cyberbullying including students who self-identify as LGBTQI+, have disabilities, or are overweight (Fraguas et al. 2019; National Academy of Sciences 2016)?
  • How effective are school-based anti-bullying interventions when implemented in the following settings?
    • High schools
    • Charter or private schools
    • Rural communities
    • Communities with lower incomes
  • What are the effects of school-based anti-bullying interventions on the following outcomes?
    • Specific mental and behavioral health outcomes (e.g., depression)
    • Educational outcomes and attainment
    • Bystander action
    • Number of students who witness bullying perpetration on others
    • Risk behaviors
    • Other forms of violence and delinquent behavior

Study Characteristics

  • Included studies were randomized trials (69 studies).
  • Studies were conducted primarily in Europe (31 studies) and North America (17 studies from the United States, 2 from Canada). Remaining studies were from Australia (3 studies), China (4 studies), South Africa (3 studies), Brazil (2 studies), Chile, Indonesia, Israel, Iran, New Zealand, Turkey, and Zambia (1 study each).
  • Studies from the United State and Canada primarily focused on students in elementary schools (10 studies), middle schools (5 studies), or both (2 studies). Only one study was conducted in high school and one study evaluated students in preschool or kindergarten.
  • Participants in U.S. studies included Black or African American students (median 16.0%; 14 studies) and Hispanic or Latino students (median 25.5%; 14 studies).
  • Seven U.S. studies reported student participation in free or reduced lunch program (median 40%; 7 studies).