Delirium is one of the most serious medical complications experienced by older patients. Emphasis on early recognition, prevention, and management of delirium underlines the need for effective services across multiple settings from community to hospitals and other institutional care settings. At present, the diagnosis of delirium is clinically based. Management strategies for delirium need to be focused on prevention and symptom mitigation. This chapter reviews the etiology, consequences, screening, diagnosis, prevention, and management of delirium in older patients.