On March 5, 2014, RAP joined the Western Interstate Energy Board (WIEB) for a webinar on forthcoming United States Environmental Protection Agency (EPA) regulations on carbon emissions from existing power plants under Section 111(d) of the Clean Air Act. David Farnsworth and John Shenot present an overview of policy options states may have for compliance, with relevant examples from Western states. They emphasize and illustrate the likelihood that compliance decisions made by state air regulators will have cross-state effects, and encourage ongoing dialogues between state air and energy regulators across the West. As states develop their compliance plans, their choices may affect utilities and merchant generators, balancing authorities and wholesale power markets, retail electricity customers, energy regulators, and others, thus making effective communication between the various industry players vital.