Despite recent declines in mortality, cardiovascular diseases are the leading cause of death in the United States today. It appears that many of the major risk factors for coronary disease have been identified. Researchers are still learning about different modifiable factors that may influence cardiovascular diseases. Socioeconomic status may provide a new focus. The principal measures of SES have been education, occupation, and income or combinations of these. Education has been the most frequent measure because it does not usually change (as occupation or income might) after young adulthood, information about education can be obtained easily, and it is unlikely that poor health in adulthood influences level of education. However, other measures of SES have merit, and the most informative strategy would incorporate multiple indicators of SES. A variety of psychosocial measures--for example, certain aspects of occupational status--may be important mediators of SES and disease. The hypothesis that high job strain may adversely affect health status has a rational basis and is supported by evidence from a limited number of studies. There is a considerable body of evidence for a relation between socioeconomic factors and all-cause mortality. These findings have been replicated repeatedly for 80 years across measures of socioeconomic level and in geographically diverse populations. During 40 years of study there has been a consistent inverse relation between cardiovascular disease, primarily coronary heart disease, and many of the indicators of SES. Evidence for this relation has been derived from prevalence, prospective, and retrospective cohort studies. Of particular importance to the hypothesis that SES is a risk factor for cardiovascular disease was the finding by several investigators that the patterns of association of SES with coronary disease had changed in men during the past 30 to 40 years and that SES has been associated with the decline of coronary mortality since the mid-1960s. However, the declines in coronary mortality of the last few decades have not affected all segments of society equally. There is some evidence that areas with the poorest socioenvironmental conditions experience later onset in the decline in cardiovascular mortality. A number of studies suggest that poor living conditions in childhood and adolescence contribute to increased risk of arteriosclerosis. Some of these studies have been criticized because of their nature, and others for inadequate control of confounding factors.(ABSTRACT TRUNCATED AT 400 WORDS)