This chapter aims to clarify the mechanisms that link the dopamine receptor gene (DRD4) and adolescent antisocial behavior. Dopamine is the key neurotransmitter that regulates brain activity, especially modulation of responses to rewards and punishments. The DRD4. allele is associated with exploratory novelty seeking, fearlessness, and reward dependence, psychological traits that may lead to both adaptive and maladaptive behavior. The findings of empirical studies attempting to link the DRD4 gene to novelty seeking and sensation seeking, however, have been mixed. Developmental criminology and developmental psychopathology provide a rich background for the trait × environment part of our model. Low self-control is the cornerstone of all major theories of adolescent delinquency. The peer domain also makes a considerable contribution to antisocial behavior. Aggressive children tend to be rejected by their peers, and this peer rejection creates a group of ostracized youths who, because of fewer opportunities to become socialized into prosocial groups, are further at risk for antisocial behaviour.