In this chapter, we discuss barriers and limits to the circular economy. We refer to numerous waste and resource managements. Barriers can be overcome by new technical efforts, better flows of information, or financial incentives, may be tomorrow or in the far future. Physical limits are those given by natural laws. The collective term “boundaries” is used for both cases, that is, barriers and limits. The boundaries are caused by many physical, chemical, technical, and economic limitations that are characterized by seven “stumbling blocks”. It is demonstrated that systemic thinking along the value chains is a crucial prerequisite to extend barriers for resource management.