This study aims to assess whether students at schools implementing Project SUCCESS (PS) have different substance use and mental health outcomes than those at schools not implementing PS. Surveys were administered to 18,151 middle and high school students from 29 school districts and 50 schools. Multivariable logistic and linear regressions controlling for individual- and school-level characteristics were used. Students at schools with PS had lower odds of past month cigarette use, vaping, alcohol use, marijuana use, past year suicide ideation, and had fewer depressive symptoms relative to students at schools without PS. Findings suggest students at schools with PS may be less likely to engage in substance use and less likely to experience mental health challenges than students at schools without PS.