To test whether communitywide health education can reduce stroke and coronary heart disease, we compared two treatment cities (N = 122,800) and two control cities (N = 197,500) for changes in knowledge of risk factors, blood pressure, plasma cholesterol level, smoking rate, body weight, and resting pulse rate. Treatment cities received a 5-year, low-cost, comprehensive program using social learning theory, a communication-behavior change model, community organization principles, and social marketing methods that resulted in about 26 hours of exposure to multichannel and multifactor education. Risk factors were assessed in representative cohort and cross-sectional surveys at baseline and in three later surveys. After 30 to 64 months of education, significant net reductions in community averages favoring treatment occurred in plasma cholesterol level (2%), blood pressure (4%), resting pulse rate (3%), and smoking rate (13%) of the cohort sample. These risk factor changes resulted in important decreases in composite total mortality risk scores (15%) and coronary heart disease risk scores (16%). Thus, such low-cost programs can have an impact on risk factors in broad population groups.