Objective: The purpose of this study was to evaluate the effectiveness of environmental activities in a school-based health program among 6th grade students (N = 2315). Methods: Students enrolled in Project Healthy Schools, a school-based health program designed to reduce childhood obesity and improve cardiovascular health, completed a health questionnaire on recent lifestyle choices including diet, physical activity, and sedentary behaviors. Baseline and follow-up data were compared between students who received educational lessons and students who received educational lessons and additional activities in the schools' environment. We calculated descriptive and one-way ANOVA statistics. Results: Students at schools with educational lessons and environmental activities reported more fruit intake (p = .046), fewer sugary beverages (p = .054) and servings of fatty/sugary foods (p = .002), and more moderate physical activity (p = .009) compared to students with educational lessons only. No beneficial effect was observed in decreasing TV viewing time. Mobile device time increased in both groups. Conclusions: The present study suggests school-based health programs combining educational lessons and additional environmental activities may improve diet and physical activity in middle school children to a greater degree than educational lessons alone.