This book illustrates two approaches for firms to shape successful circular strategies, namely, the Circular Economy and Circular Districts. The former considers firms? challenges when turning theoretical circular models into practice. Thus, it discusses the opportunities and difficulties in reshaping corporate strategies by reflecting on circular economy principles. The latter approach plays a new role within the new economy systems and this book conceptualizes and operationalizes its definition. The circular district can represent an effective way to accelerate the energy transition process by developing industrial collaborations and exploiting technology synergies to enhance circularity and achieve economic, environmental, and social targets.