The SDAS is a user-friendly, point-score system that estimates the probability that an arrested offender will test positive through urinalysis for the use of cocaine, crack, or heroin. The Scale uses information typically available at the time of arrest, including most serious arrest charge, misdemeanor/felony, race/ethnic group, age, primary source of income, and marital status to evaluate the likelihood of detecting recent cocaine-opiate use. Data show that persons between the ages of 26 and 40 and arrested for drug possession, as well as those arrested for drug sales and burglary, exhibit the highest rates of current drug abuse. Validation tests with samples of offenders processed by the Drug Use Forecasting System in Manhattan in 1987-1991 and 1992-1993 suggest that the SDAS is well-calibrated for use with this population. At least 90 percent of the persons the scale identified as having a 90 percent likelihood of drug use were actually detected as cocaine-opiate users. An initial cross-validation study conducted in four additional cities in the Northeast suggest that the scale may be useful in other jurisdictions. 25 tables and 24 references