The Drug Use Forecasting (DUF) program was established by the National Institute of Justice to further our understanding of drug use among persons who have been arrested and booked for serious crime. On a quarterly basis, booked arrestees who have agreed to participate submit to urinalysis and interviews. The resultant data provides information to each test site that allows them to observe increases and decreases in drug use over time, identify changes in the drugs of choice and observe patterns of use by different subgroups. This report discusses the background of the development of the DUF program and the rationale for its development. The methods adopted by the program are described including sampling strategy, specific procedures employed, and quality control measures. A third section of the report discusses how DUF data has been used by legislators and policymakers at some of the 24 test sites. The data is useful in helping jurisdictions allocate criminal justice resources by identifying drugs being used and trends over time. It also provides documentation of drug use among serious offenders and helps to justify law enforcement, prevention and treatment programs. Some of the specific findings of the DUF programs are listed. Evidence is presented of the severity of the drug use problem among arrestees in contrast to drug use in the general population as indicated by other testing measures. 4 exhibits