This paper examines the clinical presentation of, the biochemical abnormalities associated with, and the treatment of depressive disorders in late life. A comparison of geriatric depression (late-onset, first-episode depression) will be made to depression as it presents in childhood and middle age. Childhood onset depression is now accepted as a valid diagnostic/clinical entity. However, there is no conclusive evidence to date that pharmacologic intervention is effective in the treatment of childhood onset depressive disorder. On the other hand, major depression occurring in middle age has been shown to be quite responsive to pharmacologic interventions. Although the precise mechanism of pharmacologic intervention is unknown, certain biochemical abnormalities have been associated with middle-age onset of depression. We will discuss the similarities and differences of depression in the elderly to depression in both middle age and childhood. It is often difficult to diagnose a depressive disorder within the geriatric population. In addition to a primary depression, elderly individuals are susceptible to other syndromes which may present in a fashion similar to depression. These include depressive reactions associated with dementia and demoralization in the elderly. In addition, depression, especially in the elderly, may masquerade as other clinical entities. Following the discussion of the diagnostic difficulties associated with depression in the elderly, we will discuss potential treatment modalities for late-onset, first-episode depression. This will include an examination of common antidepressant treatments, such as tricyclic antidepressants and monoamine oxidase inhibitors, as well as other less frequently used and experimental treatment modalities.