Objective - To set out the author's views of the role of epidemiology in social psychiatry and to illustrate this role with reference to affective disorders. Method - Review of work carried out in two areas; the bearing of gender and of age on rates of affective disorder. Results - The use of sociodemographic categories to define high risk groups suggests that affective disorder may be related strongly to role satisfaction and that age may have a pathoplastic effect on the form of disorder that overrides all but the strongest social influences. Conclusions - Epidemiology is an essential tool of the social psychiatrist, but its main strength is in clarifying the nature of the questions to be asked and suggesting new lines of investigation.
