I have outlined the techniques of social systems assessment and intervention developed as a result of intervening directly in the problems of the immediate social environment of over 1,600 routine psychiatric patients. The techniques are based on an application of therapeutic community principles to real life settings outside the hospital. Concepts of leadership, role structure, and patterns of communication and reinforcement apply equally well to the social system of a childless married couple and to the neighborhood in which they live. The assessment of a social system should lead to an understanding of its structure and functioning, the external precipitants of its disturbance and the conflicts internal to the system.