ABSTRACT This paper examines the causal effect of earning a GED or vocational degree on future illicit drug use, employing random assignment into the United States’ most comprehensive education and vocational training program for at-risk youth – Job Corps – as a source of exogenous variability in degree attainment. Nonparametric bounds under relatively weak monotonicity assumptions are constructed to allow the random assignment to violate the exclusion restriction when used as an instrument. We also use a fixed effect model and propensity score weighting to supplement the results. The results from different methods suggest that degree attainment may have the most significant effect in reducing the illicit drug use of blacks, while the results for whites and Hispanics are less conclusive.