It is not atypical for young offenders to use aggression to handle problems. This exploratory study examined the contribution of social problem-solving deficit, criminal attitude, and attention-deficit/hyperactivity disorder (ADHD) symptoms to aggression among incarcerated young offenders in Hong Kong. Correlational and regression analyses were conducted to identify factors that help to predict aggression. To control for the influence of ADHD symptoms, hierarchical regression analysis was conducted to reexamine the contribution of the identified factors. The results showed that negative problem orientation (NPO) and contemptuous attitudes toward the law, court, and police (LCP) helped to predict aggression at the current moment and 3 months later. After controlling for ADHD symptoms, only LCP but not NPO remained a significant predictor of both current and near-future aggression. This finding suggests that the contribution of criminal attitude to aggression tends to be independent of the effects of ADHD and social problem-solving deficit. We conclude by discussing the theoretical and practical implications of conceptualizing aggression and improving psychological services for young offenders.