A substantial and growing percentage of older adults misuse alcohol, prescription drugs, or other substances. The number of older adults in need of substance abuse treatment is expected to more than double from 1.7 million in 2000 and 2001 to 4.4 million in 2020. One in four older adults has a significant mental disorder. Among the most common mental health problems in older persons are depression, anxiety disorders, and dementia (Bartels, Blow, Brockmann, & Van Citters, 2005). Saint Vincent Catholic Medical Centers' (New York) Department of Community Medicine operated a comprehensive ambulatory substance abuse/mental health program at the Barbara S. Kleiman (BSK) shelter for homeless men in New York from October 2006 through May 2010. This shelter was the site of the described study that was approved by the New York City Department of Homeless Services (DHS). The analyses and interpretations expressed herein do not necessarily reflect the opinions of DHS or its staff. The study concerns homeless men of all ages but the relevance to older homeless persons is evident. This is particularly so when it is recognized that chronic homelessness causes marked decline in age of survival. At BSK, shelter care, medical care, substance abuse, and mental health care were integrated in a single setting-a large urban homeless shelter. By using a continuum of addiction and mental health services, it promoted a flexible, supportive, and noncoercive environment for clients. We used the principles set forth in the Improvement Protocol (TIP) Series 35: Enhancing Motivation for Change in Substance Abuse Treatment as our evidence-based practice. We were able to incorporate the transtheoretical model of change that facilitated positive outcomes in the patient population. Other elements used in our daily activities included individual counseling, small group interactions, and facility or community-level interventions. Little or no adaptation/ modification was necessary to create the proposed treatment initiative at BSK. The project's goal was for clients to achieve sobriety and a positive drug-free social life, develop life skills and educational/ vocational training, and obtain and maintain independent living and employment. TARGET POPULATION Prior to full program implementation, a focus group was conducted using prospective candidates who met our admissions criteria. These persons were referred to us by the staff at the New York City DHS. The results of the focus group indicated that 53.6% would be Black or African American, 1.8% Asian, 26.8% White, 3.6% multiracial, and 14.2% from other racial population. By ethnicity, 21.4% self-reported to be Hispanic. Alcohol would be the primary drug of choice (46.4%); marijuana (19.6%); cocaine/crack (14.3%); heroin (5.4%); other opiates including benzodiazepines, percocet, and codeine (9.0%). The men averaged at least 6-12 months of homelessness each year. New York City was the target population's service area. RECRUITMENT Recruitment of clients for the program evaluation was done via the DHS assessment shelter system. Employed or employable clients with a reported substance abuse and/or mental health condition were referred to BSK. At intake, they received a biopsychosocial, psychiatric, comprehensive medical, and a drug screen using Drug Abuse Screening Test (DAST-10). A BSK case manager assessed clients for other unmet needs. INCLUSION CRITERIA All persons were admitted who, based on a thorough clinical evaluation, were judged to benefit from ongoing treatment for substance abuse in a program of several weekly group treatments. EXCLUSION CRITERIA Potential clients without a Diagnostic and Statistical Manual of Mental Disorders 4th Edition Text Review (DSM IV-TR) Axis I diagnosis of a substance abuse disorder or both a substance abuse and a psychiatric disorder were excluded. Target Enrollment Number targeted for enrollment (5-year target): 390. …