Delirium is a common neuropsychiatric syndrome in the elderly that can occur in several different settings caused by several different processes. It is common and causes increased morbidity and mortality to those affected. This clinical review discusses the prediction, prevention, diagnosis, and treatment of delirium in the elderly population. Several strategies to predict delirium are noted with the discussion of pharmacological and nonpharmacological trials of prevention and treatment. Diagnosis of delirium, specifically with the use of objective instruments, is discussed, as is the evidence for pharmacological and nonpharmacological treatment strategies. Discussion of the neurobiology and genetic markers for delirium may elucidate further areas for future research.