The success of voluntary renewable markets depends upon the functioning of renewable energy certificate (REC) tracking systems across the country. In a webinar hosted by the U.S. Environmental Protection Agency’s Green Power Partnership, David Farnsworth explored the systems currently in operation within the United States and their potential for tracking renewable energy attributes. These programs are electronic databases that track the attributes of power generated, and also account for the creation, ownership, and retirement of renewable energy certificates (RECs). They are instrumental in verifying compliance with state renewable portfolio standard (RPS) policies, creating environmental disclosure labels for electricity products, and substantiating voluntary green power and environmental marketing claims. The systems offer both public reports of aggregated REC data, as well as database access for government staff to determine compliance.