This study explores substance use, psychosocial problems, and the relationships to educational status in 193 adolescents (school dropouts, 63; alternative education, 46; mainstream students, 84) who attended a substance abuse treatment facility in Dublin, Ireland, within a 42-month period. For each adolescent, data on demographics, family background, substance use, psychiatric history, and offending behaviors were collected. The study found that the 3 groups exhibited statistically significant differences in their substance use problems, with the school dropouts displaying significantly more problems. The need for early detection and intervention of at-risk students, and collaborative interagency work aimed at addressing substance use, cannot be overemphasized as strategies to ultimately prevent school dropout.