With the onset of increased competitive pressures from the likes of globalisation and various other factors, there has recently been a greater focus on the systematic integration of operations within and beyond enterprises. One such area has been the integration of maintenance planning and execution with the planning and control of manufacturing. Such a novel concept is denoted as Integrated Planning (IPL). In this paper we investigate developments within this area, and propose a conceptual framework which should be used to guide subsequent advances in the field.