This study examined the roles played by parental alcohol abuse and social support, peer substance abuse risk and social support, and substance abuse risk among adolescents in South Korea. Participants were adolescents between the ages of 15 and 22 years (mean, 18), residing in Seoul city and in surrounding Kyung-gi Province. Of 259 participants, 41.3% scored 2 or more on the POSIT scale, which suggested they met the problematic criteria for substance abuse risk. Logistic regression results suggested that the influence of social support on substance abuse risk among adolescents depended on the source of support--parents or peers. These findings need to be considered in the development of intervention programs for adolescents at risk for substance abuse.