This booklet describes the symptoms, forms, causes, and treatment of depression, with particular focus on depression in children, adolescents, and older adults. Symptoms include: persistent sad or "empty" mood; feelings of hopelessness, guilt, or helplessness; loss of interest in ordinary activities; sleep disturbances; eating disturbances; thoughts of death or suicide; and restlessness and irritability. Among the disorders several forms are major clinical depression, dysthymia, bipolar depression (also called manic-depressive disorder), or a combination of disorders. Causes include genetic, biochemical, and environmental factors. Treatments include drug, psychosocial, and electroconvulsive therapy, and (still under study) experimental treatments. Childhood depression may go unrecognized when combined with other types of behavior such as hyperactivity or delinquency. Depression appears to be occurring more commonly among teenagers, whose symptoms are sometimes attributed to the "normal adjustments" of adolescence. Symptoms of depressed older adults are often misdiagnosed as senility or everyday problems of the aged. The depressed person can be helped by family and friends who maintain as normal a relationship as possible, point out distorted thinking without being critical or disapproving, acknowledge that the depressed individual is suffering and in pain, and express affection. Family and friends should not blame the depressed person for his or her condition or say or do anything to exacerbate a poor self-image. (CB)