These surveys are designed to determine the prevalence of use and nonuse of specific substances, the frequency of use among users, the frequency of specific instances of use, the volume of consumption, individuals at risk, the relationship between consumption and various consequences, and the distribution of consumption. The main problem in measurement is underreporting. In addition, the wording of questions may greatly influence the resulting consumption estimates. Problems also exist regarding the validity and comparability of data. Currently no standards exist to define good survey work. Such standards are needed, and a useful first step would be to conduct more extensive and systematic methodological reviews for each substance. An international agency such as the World Health Organization should encourage efforts to conduct these reviews. 42 references