Western Electric Company: This longitudinal study of coronary heart disease was initiated in 1957 at the Hawthorne Works of the Western Electric Company in Chicago. The male subjects were free of coronary heart disease at baseline. The medical history and physical examination were modeled after the Framingham Heart Study. Data were collected on diet, physical activity, electrocardiogram, blood hemoglobin and blood cholesterol levels, body fatness, blood pressure, height, weight, lipoprotein lipase, glucose level, and smoking.