The deinstitutionalization policy sought to prevent unnecessary admission and retention in institutions for six populations: elderly people, children, people with mental illness or developmental disabilities, criminal offenders, and, more recently, the homeless. It also sought to develop community alternatives for housing, treating, and habilitating or rehabilitating these groups. U.S. institutional populations, however, have increased since the policy’s inception by 212%. As implemented, deinstitutionalization initiated a process that involved a societal shift in the type of institutions and institutional alternatives used to house these groups, often referred to as transinstitutionalization. This entry considers how this shift has affected the care and control of such individuals from political, economic, legal, and social perspectives, as well as suggestions for a truer implementation of deinstitutionalization.