The Federal Government is expanding its collection of data on the extent and consequences of illicit drug use, although less is being done to increase data on drug-control programs. The conference participants' primary recommendations aim to ensure that the expansion is conducted so that policymakers have consistent and comparable data on various aspects of the problem. The conference also emphasized the need to improve the quality of data analysis and data dissemination. Principal recommendations regarding the estimation of the prevalence, consumption, and expenditures of drug users are that the National Household Survey on Drug Abuse be conducted annually, that data be collected on a national sample of persons in all components of the criminal justice system, that analysis and synthesis of the results of survey data collection be improved, and that the goal of data collection and analysis be to provide the basis for a reasonable and timely profile of the market for illicit drugs in the United States. Regarding the consequences of drug use and trafficking, the conference recommends that the Department of Health and Human Services experiment with methods to quantify and monitor the important health consequences of drug use through the appropriate modification of existing data series. Recommendations that pertain to program effects are that the Office of Substance Abuse Prevention or the Department of Education collect data regularly from a sample of local agencies and school districts on the nature and extent of their prevention activities, that the National Drug and Alcoholism Treatment Unit Survey coverage of privately funded treatment programs be improved, and that a mechanism be developed to assess the impact of drug law enforcement on the criminal justice system as a whole. Appended list of conference participants and data sources referenced in the report