AN understanding of the interrelationship between the goals and structure of psychiatric facilities is of importance in the development of effective treatment units. Theoretical constructs derived from systems theory^1-3 can be of value in planning and utilizing treatment settings. In this communication some of these concepts will be presented (eg, primary task, the organization as an open system, boundary control) and then applied to problems typically encountered in designing one of the most frequently misunderstood treatment institutions, the day hospital.

Primary TaskÌý While organizations may perform several tasks simultaneously and these tasks may lack a settled order of priority that persists over time, every organization has one task, a primary task, that it must perform in order to survive.¹ A university, eg, must educate, at least some of its students, a hospital must effectively treat some of its patients, an investor-owned corporation must make a profit, etc.Day