Twenty-three samples from 22 longitudinal studies assessing both bullying perpetration and bullying victimization were selected from a sample of 1,408 candidate studies using several prespecified criteria (i.e., participants ≤ 18 years of age; self-reported bullying victimization and perpetration assessed with a lag of at least 1 month but no more than 24 months; not a treatment or program study). A random effects meta-analysis was then performed on the concurrent and cross-lagged longitudinal associations between bullying victimization and perpetration in the 23 samples. A large pooled effect size ( = .40, 95% confidence interval [CI] = [.34, .45]) was obtained for the concurrent association between bullying victimization and perpetration, whereas modest to moderate effect sizes (victimization to perpetration: = .20, 95% CI [.17, .24]; perpetration to victimization: = .21, 95% CI [.17, .24]) were obtained for the two cross-lagged longitudinal correlations. The results did not change when analyses were conducted separately for traditional bullying and cyberbullying outcomes. These findings indicate that bullying victimization and perpetration correlate strongly and that their cross-lagged longitudinal relationship runs in both directions, such that perpetration is just as likely to lead to future victimization as victimization is to lead to future perpetration. Different theoretical models are proposed in an effort to explain these results: cycle of violence, general strain, and social cognitive theories for victimization leading to perpetration and risky lifestyles, routine activities, and peer selection theories for perpetration leading to victimization.