The paper describes the conceptual framework of the Waste Management Theory (WMT). WMT is a unified body of knowledge about waste and waste management, founded on the expectation that waste management is to prevent waste to cause harm to human health and the environment. The intersection of WMT with Industrial Ecology (IE) is presented and the mutual benefits of developing WMT alongside IE are described. A common interest of WMT and IE is to find a proper definition of waste. A radically new approach, based on an object-oriented modelling language is presented, to define the key concepts of the waste management domain. It is described how the goals and values of Industrial Ecology have been crucial to WMT development, by providing insights that are otherwise not considered in waste management. In turn, the Waste Management Theory acts as a filter to translate these goals and values to industrial systems, and helps selecting the tools by which they can be achieved.