Objectives. To determine the Connect intervention's effectiveness in reducing substance use among rural and tribal adolescents in northeastern Oklahoma. Methods. We conducted a 2-arm cluster randomized trial from 2021 to 2024, with 10 high schools per condition. Results. At baseline, 919 students were enrolled (mean age = 15 years), and the majority were American Indian or White. Alcohol-use days during the past 30 days was reduced by 18% per survey wave in the intervention