In the early stages of planning the Third International Conference in System Science in Health Care, the steering committee members, most of whom had participated in the first conference in Paris (1976) and the second in Montreal (1980), made some basic decisions about organization of subject matter. The earlier meetings had been very successful in bringing together specialists from the health professions and the traditional sciences. In addition to physicians and nurses, these were representatives of the disciplines of the behavioral sciences, system theory, economics, engineering, and the emergency fields of management science and informatics -all concerned with the development of health resources in a broad system context. The reported research and experience of the many disciplines represented had dealt with one or more of three concerns: 1) a major health problem, such as cardiovascular disease, or an important popUlation at risk, such as the elderly or children or workers; 2) some generic aspect of organization and decision making, including trial and evaluation ofinnovative health strategies; and 3) the methodology of research and analysis in system of health service. The challenge to the conference organizers lay in the eliciting and arranging of experiences in such a way that the health services could be seen as purposeful,living, evolving systems.