A new interview schedule allows lay interviewers or clinicians to make psychiatric diagnoses according to DSM-III criteria, Feighner criteria, and Research Diagnostic Criteria. It is being used in a set of epidemiological studies sponsored by the National Institute of Mental Health Center for Epidemiological Studies. Its accuracy has been evaluated in a test-retest design comparing independent administrations by psychiatrists and lay interviewers to 216 subjects (inpatients, outpatients, ex-patients, and nonpatients).