The present article studies the interplay of perceived peer delinquency and perceived sanction risk in crime causation. Different sets of hypotheses are formulated. From Situational Action Theory (SAT), it follows that adolescents who have many delinquent friends are more frequently exposed to a crime-conducive moral context. As a consequence, they will more often feel tempted to engage in criminal behavior, which renders them more responsive to sanction risk. Rational Choice Theory (RCT) suggests that adolescents who have no or few delinquent friends are more responsive to sanction risk because these individuals have more informal costs following from punishment to fear. These hypotheses are tested with longitudinal data from the British PADS+ study. Results provide strong support for the propositions derived from SAT. Perceived peer delinquency conditions the effect of perceived sanction risk, and sanction certainty perceptions are most influential among adolescents with a large number of delinquent friends.