In spite of the new methods of treatment and care introduced during the past fifteen years, schizophrenic patients are still liable to relapse with a recurrence of florid symptoms such as delusions, hallucinations and disturbed behaviour, and great suffering can be caused to all concerned (Brown et al., 1966). It has been shown that the onset of florid symptoms is often preceded during the previous three weeks by a significant change in the patient's social environment (Brown and Birley, 1968; Birley and Brown, 1970). Other studies have focused on the influence of more persistent environmental factors, such as the emotion expressed towards the patients by relatives with whom they were living. In an exploratory survey of discharged long-stay men it was found that close emotional ties with parents or wives indicated a poor prognosis (Brown, Carstairs and Topping, 1958; Brown, 1959). In a further study, patients were seen in hospital just before discharge, and their relatives were interviewed at home at the same time, and both were seen together at a joint interview shortly after discharge. It was found that those patients who returned home to live with relatives who were highly emotionally involved with them (as judged by ratings of the relatives' behaviour) were more likely to suffer a relapse of florid symptoms, even when the severity of psychiatric disturbance at the time of discharge was taken into account (Brown et al., 1962). Ratings of the patient's own expressed emotion showed much less involvement, and were much less highly associated with subsequent relapse. There was also a suggestion that short-term and long-term influences might have a cumulative effect; for example, that a raised level of tension in the home made relapse more likely in the event of a critical change in the patient's social environment (Brown and Birley, 1968). These facts, together with the contrasting but just as handicapping reaction of schizophrenic patients to an under-stimulating social milieu, were brought together in a more general theory of environmental influences on the course of schizophrenia (Wing and Brown, 1970). This also took account of the high physiological arousal which had been found in the most withdrawn schizophrenic patients (Venables, 1968; Venables and Wing, 1962). It was argued that in a socially intrusive environment acting upon a patient whose thought disorder was in any case liable to become manifest whenever circumstances became too complicated, a patient would tend to attempt to protect himself by social withdrawal; but this process might easily go too far, both in hospital and outside it, leading to complete social isolation and inability to care for himself. The optimum social environment, for those who remained handicapped, was seen as a structured and neutrally stimulating one with little necessity for complex decision making.