Absent legislative intervention, CAA regulation of GHGs is moving beyond mobile sources to the industrial and power facilities that emit significant U.S. GHG emissions. The authors analyze the mechanisms available to EPA for regulating such sources, and identify one, NSPS, as the most predictable, likely, and practical, i.e., knowable, pathway. Indeed, EPA announced in late 2010 that it intends to pursue this pathway. Based on the legal structure of the NSPS and EPA’s traditional approach, the authors analyze a hypothetical GHG NSPS for one sector, coal electricity-generation. This analysis indicates that efficiency improvements and perhaps biomass cofiring could be implemented through the NSPS, yielding modest but meaningful emissions reductions. Trading could also rein in costs. Though analysis is limited to one sector and does not include modeling of costs, it suggests that CAA regulation, though inferior to comprehensive climate legislation, could be a useful tool for regulating stationary source GHGs.