The Baltimore Drug and Alcohol Treatment Outcomes Study is the largest and most rigorously conducted drug treatment outcomes study that focuses on a single city. The data represent findings from 991 uninsured Baltimore residents that voluntarily entered outpatient drug and alcohol treatment through 16 publicly funded programs from 1998-1999. Two kinds of programs are included in the study, those that treat heroin addicted individuals with methadone and counseling and those that treat alcohol, heroin, cocaine, and other drug users with counseling only. Treatment outcomes represent conservative estimates of the benefits of treatment. Participants’ self-reported behaviors at treatment entry were compared with those reported at 1, 6, and 12 months thereafter. Investigators also examined objective measures of drug use and crime, including urine drug tests and official arrest and imprisonment records. The results showed that overall drug use among participants was significantly reduced as early as 30 days after treatment and remained below the pre-treatment levels at 12 months. These reductions are consistent with those found in large multi-city trials that have been conducted over the past 20 years. Urine drug testing confirmed over 70 percent of the self-reports of cocaine abstinence and over 75 percent of the self-reports of heroin abstinence. Even after 1 year from treatment entry, participants significantly reduced their heroin, cocaine, and alcohol use; decreased the number of crimes they committed; improved their psychological functioning; increased their legal income; and reduced their risk of getting and transmitting life threatening diseases such as HIV and hepatitis. These findings support the efforts of the City of Baltimore and the State of Maryland to expand and improve the city’s treatment system. Expanding the capacity of the public system will enable all city residents to have rapid access to high quality treatment services resulting in improved health and well-being for them, and their families and communities. 5 figures