Data from a general population survey of psychiatric disorder in Camberwell were used to calculate the risk of a CATEGO-defined depressive episode before the age of 65, using a modification of Strömgren's method. Current depression was defined as cases within the relevant categories of the CATEGO program and at threshold level or above on the Index of Definition (Wing et al. 1978). A past history of depression was elicited using key symptoms such as persistent tearfulness and depressed mood, already enquired after in the course of the PSE, to identify potential episodes, followed by questions to determine accessory symptoms, duration, and degree of social impairment. Clinical judgement was then used to decide whether the disturbance constituted a significant depressive episode. Risk under one set of assumptions was 46% for men and 72% for women. Using another method based on (untenably) conservative assumptions, it became 16% and 30% respectively. The status and implications of these high values are discussed, particularly for genetic studies.