The number of mixed-ethnic adolescents from multicultural families in South Korea has rapidly increased over the last several years. Although traditionally ethnically homogeneous, Korea has recently shifted toward multiculturalism, yet little research has compared mixed and single-ethnic youth on adverse outcomes in Korea and, to date, no research has done so using a quasi-experimental design. This study uses propensity score weighting with a sample of 1,156 Korean adolescents (756 inter-ethnic and 800 single-ethnic youths) to examine differences in mixed and single-ethic adolescent adverse life outcomes, including depressive symptoms, fear of crime, and victimization experiences. The results indicate that inter-ethnic heritage is associated with increases in fear of crime, but has a negative association with victimization. Findings also revealed nonsignificant differences on depression between the two groups. This highlights the need to engage in research with a strong emphasis on eliminating confounding effects. Implications for further research are discussed.