American Indians residing on-reservation were interviewed regarding their substance use and treatment utilization. One-third had a current substance abuse problem. Predictors included gender, tribe, age, employment status, household income, and educational attainment. Almost two-thirds of those with substance abuse problems had received no treatment within the past year. A combination of formal and informal treatment was the most common approach. Treatment utilization was predicted by gender, age, and insurance coverage. (Contains 6 tables and 1 footnote.)