This paper is concerned with the socio-medical organisation of psychiatric disorder. The main line of analysis demonstrates how different psychiatric ideologies produce different objects of professional focus and, consequently, radically different forms of therapy and therapeutic environment. By way of empirical evidence, the paper examines in some detail three contrasting contexts in which psychiatric disorder has been described and organised. The first is represented in Freud and Breuer's Studies on Hysteria, the second in the case books of a turn of the century asylum, and the third in the activities and practices of a modern psychiatric ward. By drawing on these sources of data, it is argued that an understanding of large scale changes in the organisation of psychiatric health care (such as is evident, for example, in modern trends from hospital to community care), firmly depends upon a study of the inner structure of psychiatric ideologies. Furthermore, and as a corollary of this it is chimed that appeals to extra-psychiatric (economic) interests and/or scientific (pharmacological) advances as key factors for explaining processes or organisational change (especially the process of deinstitutionalisation), are essentially misleading., I Explaining Organisational Change The transition from hospital based care for the mentally ill to what is loosely termed 'community care' has been a fact of North American and European [...]