Based on Hirschi's social control theory (1969), this study examined the relationship between attachment (an element of social bonds) and the onset of substance use among South Korean adolescents. Using discrete-time logistic regression, the study investigated how attachment to parents, teachers, and close friends was associated with the timing of first alcohol and cigarette use. A nationally representative sample of Korean youth from five waves of the Korea Youth Panel Survey (N = 3,449 at baseline) was studied. Higher levels of parent and teacher attachment were associated with delayed onset of alcohol consumption and cigarette smoking. Attachment to close friends, however, was associated with earlier onset of substance use. These findings suggest that strategies for early substance use prevention should specifically target the relationships that youth develop with parents and teachers. Furthermore, the results highlight the importance of managing youth's relationships with close friends to prevent the inadvertent negative social influence of particular types of peers.