Abstract: The circular economy aims to minimize resource inputs and waste and emission outputs of the economy and its organizational subsystems. This can benefit both financial and sustainability performance of companies. To analyze industrial implementation of the concept, the prevalent unit of analysis on the firm level is currently the circular business model. Our investigation of nine Swedish biogas companies and one branch organization indicates a range of conceptual shortcomings that challenges this approach. Our comparative case analysis points towards circular ecosystems being a more appropriate concept to describe the high level of coordination between different stakeholders necessary to implement circular systems. This increases the suitability to analyze, plan, and communicate circular economy systems on an organizational level, especially if value chain integration is low. An ecosystem perspective can thus support innovation and entrepreneurship in the context of the circular economy.