OBJECTIVE: To examine whether adult social class and childhood social class are related to metabolic syndrome in later life, independent of adult behavioral factors. RESEARCH DESIGN AND METHODS: This was a population-based cross-sectional study comprising 2,968 men aged 60-79 years. RESULTS: Adult social class and childhood social class were both inversely related to metabolic syndrome. Mutual adjustment attenuated the relation of metabolic syndrome with childhood social class; that with adult social class was little affected. However, the relation with adult social class was markedly attenuated by adjustment for smoking status, physical activity, and alcohol consumption. High waist circumference was independently associated with adult social class. CONCLUSIONS: The association between adult social class and metabolic syndrome was largely explained by behavioral factors. In addition, central adiposity, a component of metabolic syndrome, was associated with adult social class. Focusing on healthier behaviors and obesity, rather than specific efforts to reduce social inequalities surrounding metabolic syndrome, is likely to be particularly important in reducing social inequalities that affect people with coronary disease.