This book integrates the current state of knowledge on the association of neurochemical and psychological factors underlying the concept of depression or on the process and nature of the drug-induced changes that lead to recovery. Highlighting the results of two major multisite collaborative studies of the psychobiology of depression, the author demonstrates how more refined clinical methods uncover the initial behavioral actions of the drugs and chart the time course of their actions. The results disconfirm earlier textbook reported findings that these actions are delayed for several weeks beyond the almost immediate neurochemical effects. The “multivantaged” method makes possible distinguishing the clinical actions of different classes of antidepressant drugs.