This paper presents an overview of the corporate planning system which has evolved for a large multi-national corporation in the information processing business. An integrated planning system is described which relates, through a cyclic process, the objectives, strategies and action plans of the company in response to dynamic markets in environments of intense competition and technological change. Of particular interest is the combination of periodic planning events with time variable elements, which gives the system necessary flexibility. Additionally, a brief discussion of the increasing significance of management science to strategic planning is included. The computer tool and advanced quantitative techniques have greatly enhanced the value of a formal planning system. The planning process has in fact become an integral part of the management system at IBM, acting as a vehicle for decision making and delegation of responsibility. In this role, the planning system has had to be an adaptive organism, responsive to variations in management style and sensitive to the lessons of prior experience.