Schizophrenia is a complex mental disorder with interactive neurodevelopmental, genetic, environmental, and psychosocial risk factors. Before the onset of frank psychotic symptoms, predictive clinical signs, neurocognitive abnormalities, and neurobiological dysfunctions (functional and structural brain alterations and molecular genetic features) can be detected. These markers are of special interest because with an appropriate assessment, the onset and prognosis of psychosis and the therapeutic response may be predicted. In this paper, the authors review these vulnerability markers, providing a scientifically founded and clinically oriented framework for the prevention of schizophrenia.