Background: Since deinstitutionalization in the 1950s-1970s, public mental health care has changed its focus from asylums to general hospitals, outpatient clinics and specialized community-based programs addressing both clinical and social determinants of mental health. Analysis of the place of community-based programs within a comprehensive health system such as the Veterans Health Administration (VHA) may illuminate the role of social forces in shaping contemporary public mental health systems. Methods: National VHA administrative data were used to compare veterans who exclusively received outpatient clinic care to those receiving four types of specialized community-based services, addressing: 1) functional disabilities from severe mental illness (SMI), 2) justice system involvement, 3) homelessness, and 4) vocational rehabilitation. Bivariate comparisons and multinomial logistic regression analyses compared groups on demographics, diagnoses, service use, and psychiatric prescription fills. Results: An hierarchical classification of 1,386,487 Veterans who received specialty mental health services from VHA in Fiscal Year 2012, showed 1,134,977 (81.8%) were seen exclusively in outpatient clinics; 27,931 (2.0%) received intensive SMI-related services; 42,985 (3.1%) criminal justice services; 160,273 (11.6%) specialized homelessness services; and 20,921 (1.5%) vocational services. Compared to those seen only in clinics, veterans in the four community treatment groups were more likely to be black, diagnosed with HIV and hepatitis, had more numerous substance use diagnoses and made far more extensive use of mental health outpatient and inpatient care. Conclusions: Almost one-fifth of VHA mental health patients receive community-based services prominently addressing major social determinants of health and multimorbid substance use disorders. Background Care for people with psychiatric disorders has undergone extraordinary changes in the past 70 years from a focus on asylum care to a "de facto" system of diverse, largely non-institutional services [1-3]. A distinctive feature is the provision of community-based often intensive services for the most vulnerable, those long thought to be the most inadequately served [4]. In 1950, care for people with SMI, provided in over 500,000 state mental hospital beds [5], and was a target of public scorn [6]. By 1970, the majority of these beds had been closed and acute care was provided primarily in general hospitals, with longer term institutional care in nursing and board and care homes [7], and outpatient care in public clinics bolstered by newly developed antipsychotic and other psychiatric medications. By 1980, a substantial academic literature had developed decrying the failures of deinstitutionalization and the neglect of people with the