This article examines possible causal linkages between moral neutralization–a generic term for the related concepts of neutralization techniques, moral disengagement, and self-serving cognitive distortions–and aggressive behavior by using a set of repeated measures in a culturally diverse urban sample at ages 11.4 and 13.7 (N = 1,032). First, correlational analyses show a strong cross-sectional association between moral neutralization and aggression. Second, fixed-effects regressions indicate substantial within-individual association implying that the cross-sectional association cannot be explained away by population heterogeneity. The within-individual association also remains stable when controlling for a number of potential confounds, which supports the notion of a direct causal relationship. Third, results of path analyses revealed near-zero lagged effects of moral neutralization on aggression when controlling for antecedent aggression and vice versa, thus suggesting no longer-term independent causal effects in either direction. Moreover, synchronous effects of moral neutralization on aggression when controlling for antecedent aggression and vice versa are same-sized and significant. Overall, results suggest a close short-term interdependence of both constructs.