The author describes the crisis in affordable housing for individuals with serious mental illness who have extremely low incomes and outlines implications for the behavioral health system. Studies have shown that nowhere in the United States can an individual with serious mental illness who is receiving Supplemental Security Income afford housing. This has contributed to compliance issues with the Americans With Disabilities Act. The failure of housing policy to effectively address the needs of individuals with serious mental illness who are in poverty is largely to blame for the most visible and costly failures attributed to the behavioral health system: institutionalization, incarceration, and chronic homelessness. It is critical for the behavioral health field to advocate for housing policies to address the housing affordability crisis.