This chapter focuses upon social work as an institution which has a history and which interacts with other institutions in society. The arguments surrounding the increasing instability of the psychiatric definition of social work and the threats presented to it by the social disciplines is the major basis of theoretical argument in social work's knowledge base. One of the major objects of social analysis might be social worker's increasing adoption of an explicit form of social theory. Welfare has a structural place in our society which it is hard to see being eliminated but it has a changing meaning and thus a changing knowledge base. In these terms social work's knowledge base can be seen to present a contemporary attempted shift from a paradigm based upon psychiatry as an informing discipline to one based upon politics. Systems theory has a history of applications in other professions licensed by the state to intervene as a form of social control.