This is an overview of a two-phase epidemiological study of mental disorders among young adults in a ten-year birth cohort (1949–58) conducted in Israel. A sample of 4914 Israel-born offspring of Jewish immigrants was obtained by full probability sampling procedures and screened for caseness using psychometric symptom scales from the Psychiatric Epidemiology Research Interview (PERI). Those screened positive and almost a fifth of the negatives (N = 2741) were interviewed by psychiatrists using the Schedule for Affective Disorders and Schizophrenia, Israel version (SADS-I), in order to determine prevalence rates of specific disorders as defined by the Research Diagnostic Criteria (RDC). The completion rates for each interview phase were 94·5% and 90·7% respectively. Six-month prevalence rates are presented by gender, ethnic origin, and education. Approximately one-fifth of the birth cohort met current RDC criteria for a disorder at the definite level, excluding the RDC category of ‘other psychiatric disorder’. Generalized anxiety disorder and major depressive disorder were the most commonly found types. The striking findings centre on alcoholism and drug use disorder which were exceedingly rare, and the unusually similar rates of major depression for males and females. The results from this study are discussed in comparison with those obtained from other epidemiological studies.