In 1984 and 1985, research staff asked 6,406 male arrestees and 227 female arrestees charged with a variety of offenses to participate in a research interview and provide urine specimens to test for drug use. Over 90 percent agreed to be interviewed, and over 80 percent provided a urine specimen. Additional information on each subject's case processing, prior record, and subsequent criminal justice contacts was obtained from criminal justice files. Thin layer chromatography, a popular method for determining drug use, was not as effective for identifying recent drug use as the enzyme-multiplied immune urine tests. Detection of drug use through self-reports was not accurate. The use of hard drugs was mainly by arrestees over age 20; such use declined after age 35. Cocaine was most frequently detected in arrestees of all ages. Although analyses of pretrial rearrests have not been completed, rearrest findings in the 11-17 months after the index arrest indicate that arrestees with positive urine tests were more likely to have multiple rearrests. Those testing positive on more than one drug had the greatest number of rearrests. 6 data exhibits. (Author summary modified)