Treating bureaucracy as one case within a general theory of purposive organisation, Selznick argues that every organisation generates an informal structure of personal ties and control techniques, and that this structure quietly rewrites the goals the organisation says it pursues. He builds the claim from Roethlisberger and Dickson's shop-floor study, Barnard's account of executive function, and Waller and Henderson's work on reformatories and other institutions of segregative care. Daily operating problems displace professed aims because only the former specify concrete action. Delegation then splits the interests of those who initiate action from those employed to carry it out, and the resulting contest over control pushes officials to build power bases independent of the membership that hired them. Selznick catalogues the ideologies leaders construct to defend those positions, including the identification of any opposition with enemies of the group itself. He reads Michels sympathetically while insisting that bureaucratic drift is a tendency whose strength must be measured case by case, and countered.