Closed loops depict supply chains for which Original Equipement Manufacturer reintegrate their returned products into their own production network. While the reverse logistics research has extensively addressed the technical aspects of product reintegration, very few insights are available on whether OEMs should commit themselves to a closed-loop. The structure of the monograph is aligned to the decision-making process of Original Equipment Manufacturers willing to investigate the potential of closed-loops. This decision-making process is structured around fundamental questions managers are expected to answer prior to running a circular supply chain: Does a closed-loop fit with the corporate objectives? Is it profitable to run a closed-loop? How should OEMs deal with free-riders competition? Which product/technology/location setup leads to a profit-maximizing supply chain? The planning framework is finally applied to two case studies from the tire and the computer industry.