Abstract For thirty years research has been consistently demonstrating the validity of the concept of ‘High Expressed Emotion’ (HEE). After early pioneering work by Brown it was established that environmental influences, particularly, the emotion expressed by relatives to sufferers of schizophrenia, are strongly implicated in relapse. Consequently, the predictive validity of HEE has been revealed in a number of cross-cultural studies around the world. In addition, there is strong evidence from well designed intervention studies, that relapse, in schizophrenic clients living at home, can be prevented by the manipulation of social and environmental factors. The combined body of research that has now accumulated allows an hypothesis to be made about the aetiology of the illness, schizophrenia, itself. This theory has been described as the ‘stress vulnerability’ model. The paper concludes that psychosocial intervention strategies are effective but that, unfortunately, to date, their application has been mostly restricted to the intervention studies themselves.