The aim of this study was to further our understanding of the link between social anxiety and substance use in adolescents, in particular the role susceptibility to peer pressure plays in this link. The relation between social anxiety and susceptibility to peer pressure was studied in two community samples (n=534 and n=117) each consisting of two age groups (12-13 and 15–17 years). The relation of these two variables with substance use was evaluated in the second sample using regression analysis. Social anxiety was related to susceptibility to peer pressure in both groups and not related to substance use in the younger group and negatively related to substance use in the older group. Susceptibility to peer pressure acted as a suppressor in the relation between social anxiety and substance use. Results suggest that socially anxious adolescents basically avoid substance use but, if susceptible, may yield to peer pressure and start using substances. Parents, teachers, and therapists should be aware of this susceptibility to possibly negative peer pressure of socially anxious adolescents.