Process planning is the activity of determining the manufacturing operations needed to produce a product. The knowledge work of process planning has been thoroughly investigated. Several ideas to automate process planning have been proposed but their success in practice has not yet been realized. Little attention has been given to design as an inevitable element in process planning and the role of human expertise in process design. From the premise that competent planners are a primary source of productivity this paper discusses process design, the role of human expertise and how CAPP systems could support human decision making.