Few studies have explored the relationship between individual and combined multiple indicators of socioeconomic status across the life course and the metabolic syndrome, or attempted to understand the mechanisms underlying any associations. The present study examined the associations between 4 indicators of socioeconomic status, individually and in combination, and metabolic syndrome risk in a study of male US veterans and examined the influence of health behaviors, intelligence, and psychologic distress on these associations. Participants (N = 4253) were drawn from the Vietnam Experience Study. From military service files, telephone interviews, and a medical examination, occupational, sociodemographic, health behavior, intelligence, psychologic, and health data were collected. The 4 indices of socioeconomic status were as follows: education achieved, early adulthood income, household income in midlife, and occupational prestige in midlife. Metabolic syndrome was diagnosed from the following: body mass index, fasting blood glucose or a diagnosis of diabetes, blood pressure-a diagnosis of hypertension or taking antihypertensives, high-density lipoprotein cholesterol, and triglyceride levels. In models that adjusted for age, men in the lower 2 groups on the combined measure of socioeconomic status experienced a higher risk of metabolic syndrome. This association was accounted for mainly by education achieved, household income in midlife, and occupational prestige in midlife. Intelligence appeared to explain much of this association. Combined socioeconomic status measures across the life course were related to metabolic syndrome but in a threshold rather than dose-response manner. Intelligence appeared to mediate this relationship.