Incarceration may be an overlooked reason for treatment non-completion experienced disproportionately by African Americans. This study utilized multilevel logistic regression to model treatment non-completion due to incarceration using the 2015-2016 Treatment Episode Dataset-Discharges. Among a sample restricted to treatment non-completers (n = 306,008), 5% terminated treatment because they became incarcerated (n = 13,082), which varied widely by demographics and by state. In Idaho, 46% of African Americans terminated treatment because they became incarcerated. Women had lower odds of treatment non-completion than men, and the effect of sex was strongest among African Americans (adjusted odds ratio [aOR] = 0.30, 95% confidence interval [95% CI] = 0.26-0.34). Among men, all racial/ethnic minority groups demonstrated significantly higher odds of treatment non-completion due to incarceration compared with Whites, and the strongest effect was among African Americans (aOR = 1.37, 95% CI = 1.29-1.44). Incarceration as a reason for treatment non-completion disproportionately affects African Americans and men and varies by state. Interventions targeting incarceration alternatives should be availed to racial/ethnic minorities already participating in treatment.