Cyber delinquency in adolescence is a particular area of concern for psychologists owing to its association with several mental health issues and its potential link with offline delinquency. This longitudinal study examined the stability of changes and directions of influence in adolescents' cyber delinquency, aggression, and offline delinquency across a 4-year period. Our sample consisted of 2,280 adolescents who participated in the Korean Children and Youth Panel Survey conducted by the National Youth Policy Institute in Korea, from 2011 to 2015. Using autoregressive cross-lagged modeling, we found that changes in cyber delinquency, aggression, and offline delinquency were stable over time. There were also multiple cross-lagged effects from early to middle adolescence: cyber delinquency influenced both offline delinquency and aggression, and aggression influenced both cyber and offline delinquency. However, from middle to late adolescence, the only significant effect was that of cyber delinquency on offline delinquency.