Postoperative delirium is recognized as the most common surgical complication in older adults,occurring in 5% to 50% of older patients after an operation.With more than one-third of all inpatient operations in the United States being performed on patients 65 years or older,it is imperative that clinicians caring for surgical patients understand optimal delirium care. Delirium is a serious complication for older adults because an episode of delirium can initiate a cascade of deleterious clinical events, including other major postoperative complications, prolonged hospitalization, loss of functional independence, reduced cognitive function, and death. The annual cost of delirium in the United States is estimated to be $150 billion. Delirium is particularly compelling as a quality improvement target, because it is preventable in up to 40% of patients; therefore, it is an ideal candidate for preventive interventions targeted to improve the outcomes of older adults in the perioperative setting. Delirium diagnosis and treatment are essential components of optimal surgical care of older adults,yet the topic of delirium is under-represented in surgical teaching.