This ecologic study evaluated the association between school policy allowing students to purchase sports drinks from school vending machines and school stores and student body mass index (BMI). Data were from surveillance surveys of Minnesota secondary schools (n = 238) and students (n = 59,617), administered in 2012 and 2013, respectively. We used generalized linear models to assess the association between policies and mean age- and sex-adjusted BMI percentile. In adjusted multivariate analysis, school policy was positively associated with BMI percentile (P = .005). School policy restricting student access to sports drinks at school may contribute to decreasing consumption of sport drinks among school-aged youth and improving student weight outcomes in this population.