The CIDI is a fully standardised, structured interview for the assessment of psychiatric disorders according to DSM-III-R and proposed ICD-10 criteria. The development of this interview has been the collaborative effort of researchers from 18 sites around the world. In a field trial to test the cross-cultural acceptability and reliability of the questions, there was found to be high acceptance and excellent reliability for the substance use questions, problems with the lengthy alcohol section, and difficulties translating relevant substance use concepts into different languages. There is therefore room for further improvement in the substance-related questions. There proved to be differences between ICD-10 and DSM-III-R regarding substance abuse and dependence disorders.