Stability and Change of Bullying Behavior in Children and Adolescents: A Meta-Analysis of Longitudinal Studies

Although extensive research has examined bullying across childhood and adolescence, findings regarding its developmental course remain inconsistent. Understanding bullying development requires distinguishing between two complementary indicators: rank-order stability, which captures how individuals maintain their relative positions over time, and mean-level change, which captures how the average levels of the behavior shift across the population. To clarify these issues, the present study comprehensively synthesized the available data on rank-order stability (represented by test-retest correlation coefficients) and mean-level change (represented by standardized mean-level difference) of bullying from 197 longitudinal studies (202 samples, N = 286,853, M_age = 12.32 years, 50.64% female) published from 2002 to 2023. Results indicated that both bullying perpetration and victimization were found to be highly stable over time. This stability increased with age but weakened as the time lag between assessments became longer. In addition, analyses of mean-level change revealed an increase in bullying victimization, but no consistent change in perpetration. While the increase in bullying victimization diminished with age, the increases in both bullying perpetration and victimization became more pronounced as the time lag expanded. The stability and change of bullying behavior also differed across studies conducted in various regional/ethnic contexts and those employing specific measurement properties. Overall, these findings clarify the developmental course of bullying across childhood and adolescence by distinguishing between the persistence of individual differences and shifts in average levels at the population level, providing an empirical foundation for designing more targeted prevention and intervention strategies.