The ICAP Guide to Linking Emissions Trading Systems provides an overview of emissions trading systems (ETSs) and their potential for linking. The authors discuss the benefits and challenges of linking ETSs, including improved efficiency and reduced emissions. The guide also covers the technical and legal considerations for linking ETSs, as well as the potential for linking ETSs with other policy instruments. Overall, the guide provides a useful resource for policymakers and practitioners interested in exploring the potential of linking ETSs.