Reflecting on the fast-growing number of adolescents involved in part-time work in South Korea, we pay special attention to the effects of part-time work on school disengagement in this age group. While research on this issue in Korea is still scarce, a handful of existing studies have documented the undesirable effects of part-time work on problem behaviors among adolescents. Conclusions on whether or not such undesirable effects stem from differential socialization formed through part-time work experiences remain controversial, however, because the issue of differential selection among the adolescent population involved in part-time work remains unsolved. Utilizing propensity score matching analyses among a sample of 1365 employed adolescents extracted from data from the Korean Education Employment Panel during a period between 2004 and 2007, we find that part-time work has significant undesirable effects on school disengagement behaviors among adolescents, even after controlling for preexisting differences between groups. Implications for research in terms of differential socialization perspectives and practical policies are discussed.