The chapter studies the functioning of the so-called “voluntary” carbon offset market, a market in which moral controversies take place. The analysis dwells on the theoretical framework that enables us to study the functioning of a contested market through particular devices. The chapter seeks to contribute to the literature on moral struggles within markets by focusing the attention on one specific device: relational work, including several dimensions like meeting between seller and buyer, establishing contracts and maintaining the relationship with clients in the long run. By studying relational work, the authors highlight how this basic market activity is a crucial device that makes it possible for a contested market to continue to exist.