Abstract The day hospital has been seen as an instrument of two policies: community care and the development of general practice. An experimental day hospital was studied which is run by three general practices, and this paper illustrates tensions between the working categories of general practitioners, and the definitions of patients implied by the two policies. As regards the policy of community care, it was found that the general practitioners had difficulty in matching their working categories with some of the principles of community care set out for the hospital by its planners. These principles obliged them to see the hospital's functions in terms of therapy and discharge, but in practice some GPs were concerned with problems which seemed intractable in such terms. As regards the development of general practice, policy was aimed at developing the technical practice, the social/psychological skills, and the preventive function of GPs. In the result, preventive efforts were generally increased, but other developments were attempted only by particular groups of GPs. One group stressed the technical, and another the “social” line of development. Difficulties were encountered by the “social” line in interpreting the present formulation of policy. In general, concern with developing the technical and preventive scope of GPs tended to transformthe meaning of policies for community and social care.