The book brings together into a single text the interrelated but different research efforts to translate the current evidence on risk and outcome of severe mental disorders into a preventive perspective. The book also introduces a holistic approach to prevention in mental health, by combining biological, psychological and environmental evidence that attempts to blunt the risk and reduce the number of individuals with mental health vulnerabilities who eventually progress to the manifestation of a severe mental disorder. Finally, the book wants also to highlight the possibility to overcome the single disorder-oriented preventive approach in an attempt to intercept a wider at-risk youth population and explore clinical research areas underperformed where future efforts will have to concentrate.  Mental health problems have their peak of incidence during the transition from childhood to young adulthood, interesting up to 20% adolescents.