The concept of a dependence syndrome with graded levels of severity was originally derived from work with alcoholics. The applicability and clinical utility of the dependence syndrome across a wider range of substances was examined as part of the DSM-IV field trials. When using a criterion count method to assess severity, it was found that persons cluster at different severity levels according to the drug on which they are dependent. Across all drug classes, severity correlated reasonably well with measures of quantity and frequency of use and with associated problems. The relationship between severity ratings and outcome was not tested, however data from other studies indicate that severity is only one of many factors that can influence outcome.