This paper provides an overview of the Black Report, published in Britain in 1980. It outlines its place in the history of British concern about socio-economic differentials in death rates since the mid-19th century, and suggests continuities in suggested explanations for these, a particularly persistent thread being debates between environmentalists, hereditarians, and those emphasising personal ignorance or irresponsibility. It introduces a distinction between "hard" "soft" versions of the Black Report's four explanatory models for inequalities in health (artefact, selection, behavioural and materialist), points out that the working group rejected the "hard" rather than the "soft" versions of the first three and espoused the "soft" version of the last, and suggests that the rather polarised debate about these explanations that followed can be understood in the light of the contemporary political context and a tendency to confuse the "hard" and "soft" versions. Methodological and empirical developments since the report are summarised, attention being drawn to seven themes which raise important issues for future research: the ubiquity of socio-economic differentials across industrialised countries, continuing or increasing differentials, stepwise gradients, interest in psychosocial mechanisms, the hypothesis of biological programming in utero or infancy, controls for behaviour, and evaluations of interventions. The overall conclusion is that we need more detailed studies of the mechanisms which generate and maintain social inequalities in health, and of interventions to reduce such inequalities.