This 2020 report from Climate Xchange surveys the policy options for carbon pricing at the Independent System Operator (ISO) level. ISOs coordinate real-time electricity flow, ensure fair competition, and facilitate long-term grid investments. Seven regionally-based ISOs operate two-thirds of all electricity delivered in the United States, and are tasked with supplying affordable and reliable electricity. This report surveys where ISOs sit in the federal electric regulation hierarchy, the status of carbon pricing efforts at different ISOs, and future challenges.