This study was designed to examine the agreement of DSM-IV alcohol and drug use disorder diagnoses generated by three WHO/NIH diagnostic instruments, the AUDADIS-ADR, the CIDI, and the SCAN. This substudy, conducted in three countries, Greece, Luxembourg, and the United States, was part of the larger joint project on diagnosis and classification of mental disorders and alcohol and drug-related problems, which was initiated to evaluate the cross-cultural applicability of the instruments and the criteria. Overall, concordance among the three assessments was good for alcohol and opiate dependence, fair to good for cocaine and sedative dependence, and low for amphetamine dependence. Cannabis dependence concordance was significantly more discrepant than any other substance. Agreement on abuse was low for all substances examined. In addition, the concordance of DSM-IV criteria for each substance was examined. Finally, reasons for discrepancies in responses among assessments were examined, based on discrepancy interview protocol methodology. Further investigation will help to refine these instruments in order to provide a more thorough understanding of alcohol and drug abuse diagnoses.