The present volume contains the lectures of the symposium on "Risk and Protective Factors in Schizophrenia - towards a conceptual Model of the Disease Process", which was held at the International Science Forum of the University of Heidelberg on October, 2001. The topics of the program were "Genetic risk factors and gene environment interaction", "Psychotic and negative symptoms in the general population as risk-factors", "Etiological risk factors in embryonal life, childhood and adolescence", "Prepsychotic prodromi and stage models of the development of psychosis", "Brain development, structural and functional morphology of the early course", "Urban versus rural life, migration and social chains as causal risk factors?", "Psychological and neurobiological (estrogen, erythropoietine) protective factors". The book covers a wide scope of recent research and knowledge about schizophrenia.