1. About 15% of the general public will suffer from major depressive disorder sometime in their life, but fewer than one in three will be accurately diagnosed and treated. 2. About 10% to 15% or more of major depressive conditions are caused by general medical illnesses or other conditions. Generally, treat the associated condition first. If the depression persists after treatment, major depressive disorder should be diagnosed and treated. 3. In over 50% of depressed outpatients, antidepressant medication caused marked improvement or complete remission of their depressive symptoms. Several forms of short-term psychotherapy are effective for mild or moderate depression; combined treatment should be considered in certain situations.