This brief compiles estimates from several different federal agencies, and calculates that the economic benefits of the emissions cap in the Waxman-Markey bill likely dwarf the costs by as much as 9-to-1 or more. The benefit-to-cost ratio was determined using the EPA’s previously released (and peer reviewed) cost estimates and a newly released “social cost of carbon” estimate from an interagency process which provides a conservative dollar figure for the benefits of greenhouse gas reductions.