INTRODUCTION: Exposure to racial discrimination has been consistently linked with risk for substance use. However, outside of externalizing and affect-based factors, few other mechanisms have been examined. One potential candidate is locus of control, a learning processes that involves the degree to which one attributes rewards as resulting from their own control (internal locus of control) versus outside control (external locus of control). There is evidence that exposure to stressors is associated with locus of control, with a separate body of literature linking locus of control with substance use. Thus, it is plausible that locus of control may be a mechanism underlying the relationship between racial discrimination and substance use. METHODS: The current study investigated this pathway among 503 racial/ethnic minority adults aged 18-35 who completed an online questionnaire including measures on racial discrimination related stress, locus of control, and substance use. RESULTS: Results indicated a significant indirect effect between racial discrimination related stress, two external domains of locus of control (i.e., powerful others and chance), and substance use. A significant indirect effect was not found for internal locus of control. CONCLUSION: These findings expand our understanding on potential mechanisms that underlie the racial discrimination-substance use risk pathway among racial/ethnic minority adults, which may in turn provide important targets for substance use intervention programming.