A cross-national study of bullying and victimization among adolescents in 40 countries found significant variations in prevalence rates. Boys reported higher rates of bullying than girls in all countries, while girls experienced higher victimization rates in 29 of 40 countries. Rates of victimization decreased with age in 30 of 40 countries for boys and 25 of 39 for girls. Baltic countries had higher bullying and victimization rates, while northern European countries had the lowest. In six countries, specific types of bullying were examined, revealing that boys reported higher rates of direct physical and verbal bullying, while girls were more likely to engage in indirect bullying. Age-related patterns showed that direct bullying decreased with age, while indirect bullying increased. Gender differences were also observed, with girls more likely to use indirect aggression. The study highlights the need for culturally adapted interventions to address bullying, as prevalence varies widely across countries. The findings suggest that bullying is a global public health issue requiring population-level interventions. The study used self-reported data from nationally representative samples of 11, 13, and 15-year-olds, with a total of 202,056 participants. The results indicate that bullying and victimization are influenced by cultural, social, and developmental factors, and that age and gender differences are significant. The study underscores the importance of understanding these variations to develop effective prevention strategies.A cross-national study of bullying and victimization among adolescents in 40 countries found significant variations in prevalence rates. Boys reported higher rates of bullying than girls in all countries, while girls experienced higher victimization rates in 29 of 40 countries. Rates of victimization decreased with age in 30 of 40 countries for boys and 25 of 39 for girls. Baltic countries had higher bullying and victimization rates, while northern European countries had the lowest. In six countries, specific types of bullying were examined, revealing that boys reported higher rates of direct physical and verbal bullying, while girls were more likely to engage in indirect bullying. Age-related patterns showed that direct bullying decreased with age, while indirect bullying increased. Gender differences were also observed, with girls more likely to use indirect aggression. The study highlights the need for culturally adapted interventions to address bullying, as prevalence varies widely across countries. The findings suggest that bullying is a global public health issue requiring population-level interventions. The study used self-reported data from nationally representative samples of 11, 13, and 15-year-olds, with a total of 202,056 participants. The results indicate that bullying and victimization are influenced by cultural, social, and developmental factors, and that age and gender differences are significant. The study underscores the importance of understanding these variations to develop effective prevention strategies.