The study of occupational mortality involves the systematic tabulation of mortality by occupational or socioeconomic groups. Three main methods are used to conduct these studies: cross-sectional studies, death certificate studies, and follow-up studies. Cross-sectional studies were undertaken in England and Wales from 1851 to 1979–1983, and these studies have provided key data on social inequalities in health. Death certificate studies have been used for identification of occupational groups with high excess risks from specific diseases. Follow-up studies require linkage of individual records, typically from censuses and death certificates. They have been undertaken in, for example, all the Nordic countries. The follow-up studies have shown a high mortality for all marginal groups of the labor market, a social gradient in overall mortality, low mortality among farmers, and a widening gap between the mortality rates of blue- and white-collar workers.