In 1996, DUF program sites in 23 major metropolitan areas collected data from 19,835 adult male arrestees, 7,532 adult female arrestees, 4,145 juvenile male arrestees, and 645 juvenile female arrestees. Urinalysis data showed that marijuana use among adult male arrestees increased from the year before at almost every site. Twelve sites showed decreases in cocaine use among adult males, nine sites showed increases, and two sites showed no change. In 1996, increasing rates of marijuana use were noted across all age categories of adult males. While cocaine use among male arrestees continued to decline or remain stable in many DUF cities, remarkable increases were noted at several program sites. Opiate positives among adult male arrestees remained low relative to cocaine and marijuana. At most program sites, the rate at which male arrestees were found positive for at lease one drug increased over the last year. The percentage of very young males testing positive for marijuana increased sharply at most program sites. The median rate for opiate test positives was 2 percent among the youngest male arrestees. At 20 of 21 program sites collected data on females, the fraction of adult female arrestees testing positive for marijuana increased. Adult females exhibited higher prevalence rates for cocaine use than adult males. Generally, opiate use among adult females remained stable or increased slightly, and the percentage of female adults testing positive for at lease one drug increased overall. Decreases in cocaine use for every young female arrestees were less dramatic than in the previous year. Female arrestees under 21 years of age had the highest percentage of marijuana positives among adult females. The prevalence of opiate use varied considerably across program sites for the youngest female arrestees. Marijuana use rose sharply and cocaine use was up slightly among male juveniles. Overall, cocaine use was much higher for boys out of school than for boys in school. Methamphetamine use continued to be detected mainly at western program sites, and adult females showed greater methamphetamine use than adult males. While arrestees continued to use methamphetamines in greater percentages than blacks and Hispanics. Trends in adult and juvenile are reviewed, and site reports are included. Tables and figures