This chapter provides a historical overview of the United States mental health system to contextualize the current laws, policies, and practices. This chapter covers the early treatment of persons with mental illnesses, the rise of moral treatment, and the establishment of hospitals. Major political shifts led to discrimination and poor treatment, including forced sterilization. Several factors, including fiscal concerns and increased civil rights for patients, led to the deinstitutionalization movement, which shifted care from institutions to community-based treatment. The economic pitfalls resulted in individuals being released into the community without adequate services or support. The chapter concludes with the social consequences of deinstitutionalization, including homelessness and incarceration. This chapter explains how jails now assume most institutionalized supervision and treatment for those with mental illnesses.