Persons with symptoms of acute mental illnesses present problems for jail management. Jails have a constitutional duty to provide psychiatric services to all persons in need of such care. However, mental health resources are frequently insufficient to meet the many needs of persons with mental illnesses in jails, and are often inaccessible to those released to the community. This study focuses on the experiences of a cohort of detainees (n = 379) with mental illnesses who have been incarcerated in seven U.S. jails. Data gathered include criminal and demographic characteristics, mental health services received by the detainees in jail, discharge planning activities by jail staff, and community-based outcomes after release. This is primarily a descriptive study depicting typical experiences and processes related to detainees with mental illnesses. The goal is to provide information to support more detailed studies on the effectiveness of mental health-criminal justice linkages.