Production planning has been an integral part of industry since the beginnings of craft production. Basic quantitative research in this area is at least 50 years old (Modigliani and Hohn 1955). However, it is widely recognized that there are significant gaps between the research problems addressed, the state of industrial practice, and the needs of the industrial community. It is our experience that production planning is viewed as a narrow function at the interface of production and sales, and the basic modeling and solution approaches associated with this view have remained largely unchanged for several decades.