Objective. This study examined the concurrent diagnostic validity of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) across alcohol and drug dependencies, major depression, anxiety disorders and ASPD. The Schedule for Clinical Assessment in Neuropsychiatry (SCAN) was selected as the comparison instrument because it arises from a different tradition and uses a different format for its administration. The SCAN has been shown to be valid and applicable cross-culturally. Method. Subjects included 38 men and 42 women volunteers from another study and from an outpatient psychiatry clinic. Selected sections of both the SSAGA and the SCAN interviews were administered to all subjects, approximately 1 week apart, in a randomized order. Because the SCAN does not assess Antisocial Personality Disorder (ASPD), the ASPD section of the Structured Clinical Interview for DSM-III-R (SCID) was substituted for this comparison. Results. The Kappa statistic was used to measure concordance between the two instruments. Kappa for alcohol dependence was in the acceptable range (0.63). Kappas were lower for sedative dependence (0.48) and for cannabis dependence (0.53), but higher for cocaine and stimulant dependence (0.85) and for opioid dependence (0.73). Kappa for major depression and the ASPD diagnoses were high (0.71 and 0.70), but slightly lower agreement was found for panic disorder (0.62). Kappa for social phobia was 0.47. Conclusion. These data, combined with results from two previous studies which examined reliability, indicate that the SSAGA is a highly reliable and valid instrument for use in studies of a variety of psychiatric disorders, including alcohol and drug dependence.