The author fundamentally questions the traditional concept of the disease-entity (or several disease entities) of ‘schizophrenia’ and discusses an alternative concept, based on vulnerability and information-processing. According to this, schizophrenia-like psychotic phenomena develop in three phases. In the first, premorbid phase, combined biological (genetic and possibly other organic) and psycho-social influences lead to a premorbid ‘vulnerability’, characterised by a low tolerance of cognitive and emotional stress, corresponding to an insufficient capacity for the adequate processing of complex information. In the second phase, stressful life-events can lead to unique or repeated acute productive psychotic episodes. The third phase, that of long-term evolution, depends more on psycho-social influences than on biological factors. Under unfavourable conditions, it may lead to predominantly unproductive residual states of various degrees, which can largely be understood as regulatory mechanisms to restrict stressful over-stimulation. There is no clearly delimitable disease entity of schizophrenia with constant causes, psychopathological picture, or course, but rather a multi-conditioned life-process, occuring in people with a particular vulnerability, interacting with complex life-events and circumstances. This new concept has important consequences for therapy and prevention.