Giovanni Fava and Eliana Tossani of the University of Bologna review the literature on how depressive illness begins. Depression does not come out of the blue. There are clear warning signs that patients should know and allow an early intervention. The aim of this review was to survey the available literature on prodromal symptoms of unipolar major depression. Both a computerized (Medline) and a manual search of the literature were performed. In a substantial proportion of patients with depression a prodromal phase can be identified. There is a relationship between residual and prodromal symptomatology (the rollback phenomenon). Appraisal of prodromal phase of major depression has important implications as to pathophysiological models of disease and relapse prevention. It may allow a staging system of depressive illness which may yield more enduring results in the therapeutic efforts. Psychotherapy and Psychosomatics