Objectives This study conducted a meta-analysis in order to comprehensively analyze the effect size on variables related to relational aggression.
 Methods 149 studies were selected among the papers published in South Korea and other countries, from 2010 to March 2020, variables related to relational aggression were extracted. Total effect size of variables related to relational aggression was calculated, next each variables were classified into risk and protection variable groups, and into individual internal, family environment, peers and school environment, and social environment variable groups, and checked the overall effect size. Finally, the moderating effects by age, gender, culture were analyzed in each variable group.
 Results As a result of the analysis, it showed medium effect size in all variable groups. Specifically, the effect size of peers and school environment variable group in the risk variable group and the effect size of social environment variable group in the protection variable group were larger than other variable groups. Psychopathy and externalizing behavior problem in the individual internal variable group, and class environment, aggression victimization, and negative teacher relation in the peers and school environment variable group were shown to have a large effect size. In addition, individual internal variable group and family environment variable group in the risk variable group had moderating effect by age, family environment variable group in the protection variable group had moderating effect by gender. The moderating effect of culture was confirmed in individual internal variable group among the protection variable group.
 Conclusions Based on the above results, the suggestion for multilateral interventions to relational aggression and limitations of this study were discussed.
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