Approximately 16% of the single adult homeless population suffers from some form of severe and persistent mental illness (U.S. Conference of Mayors, 2005). Despite the disproportionate number of severely mentally ill people among the homeless population, increases in homelessness are not attributable to the release of severely mentally ill people from institutions. Most patients were released from mental hospitals in the 1950s and 1960s, yet vast increases in homelessness did not occur until the 1980s, when incomes and housing options for those living on the margins began to diminish rapidly. According to the 2003 U.S. Department of Health and Human Services Report, most homeless persons with mental illness do not need to be institutionalized, but can live in the community with the appropriate supportive housing options. However, many mentally ill homeless people are unable to obtain access to supportive housing and/or other treatment services. The mental health support services most needed include case management, housing, and treatment.