In the last few years ways of thinking in psychiatry have undergone considerable change thanks to advances in the fields of morphology and plasticity of the CNS, particularly with regard to schizophrenic and mood disorders. In addition, the rapid and considerable development of neuroimaging techniques (CT, MRI, PET and computerized EEG) and of molecular genetics (through DNA recombinant meth­ odologies) have widened the approach to these disorders in a way unimagined a few years ago. These advances and the new etiopathogenetic hypotheses that have sprung from them were the central theme of the Second International Meeting on Schizophre­ nia "Morphology and Plasticity of the Central Nervous System - A Challenge for Psychiatry of the Nineties" which was organized by the Association for Research on Schizophrenia (ARS), the Schizophrenia Research Center of the Institute of Psychiatry of the University of Milan and the T. and F. Legrenzi Foundation, held in Milan on October 22-24, 1987. This book contains the contributions from participants of the meeting, which took place in a warm and friendly atmosphere and marked by lively and exhaustive discussions on the various papers. The contributions were recently revised for the present publication. We would like to express our appreciation to the book's contributors for the high quality of their reports.