Late-life depression is a common but underrecognized and undertreated mental illness that may impose enormous disability on patients and families. Diagnosis is often complicated by comorbid medical illness, cognitive impairment, and adverse life events. Early intervention with a combination of education, psychotherapy, and antidepressant medication is recommended. Choice of specific agents requires consideration of symptom profile, tolerability, drug interactions, and compliance. Older patients may respond more slowly to treatment than younger patients and may more readily experience chronicity and recurrence.