A CSS is a multi-actor entity in which interdependent actors play complementary roles. These include for-profit companies, public services, governmental bodies, municipalities and cities, academic & research institutions, non-profit organizations, consumers, and citizens. Such an Ecosystem is a complex systemic undertaking, especially if viewed as evolving in time and operating in regional Market conditions. It emerges or is created around a common, system-level goal related to resource circularity, and may involve the creation of CE knowledge, CE businesses, and economic value4. There are technologies to select and configure, barriers to overcome, risks to predict and manage, instruments, business models, and governance conditions to be considered and optimized. The conceptualization of a CE/CSS ecosystem and the regional market is a fundamental issue for any research project based on this theme. Where to draw the boundaries of the ecosystem, what the relevant structure is, and how the ecosystem evolves are important issues.