The Leeds Dependence Questionnaire (LDQ) has been developed as pan of a treatment evaluation package. The LDQ is a 10-item, self completion questionnaire designed to measure dependence upon a variety of substances; it has been shown to be understood by users of alcohol and opiates. The questionnaire was designed to be sensitive to change over time and to be sensitive through the range from mild to severe dependence; the follow-up data are insufficient to demonstrate change over time, but are encouraging. It is expected that both clinicians and researchers will find it useful to have a single measure relating to substance use, but not limited by specific substances. All items are scored 0-1-2-3; there are no normative data. The procedure for establishing content validity is described and estimates of concurrent, discriminant and convergent validities are reported; these validities are thought to be satisfactory. A principal components analysis produced a single factor accounting for 64% of the variance. Cronbach's alpha was 0.94. Test-retest reliability was found to be 0.95.