This study investigated relationships between social variables and body mass index (BMI) in 2465 men and 2792 women aged 25 to 74 in six upper midwestern communities. After controlling for age and cigarette smoking status, BMI was significantly related to education, income, occupation, and marital status in both men and women. SES variables tended to be inversely related to BMI, with a steeper gradient for women than for men. A curvilinear trend was noted, however, in that social status tended to be lower at both ends of weight distribution than in the middle. The relationship between marital status and BMI was also found to be curvilinear. Highest rates of marriage were in the middle portion of the weight distribution for both sexes.