In June 2009, the U.S. House of Representatives passed a comprehensive climate and energy bill, the American Clean Energy and Security Act (H.R. 2454). The U.S. Senate has been considering a number of related proposals, ranging from “energy only” bills, such as the American Clean Energy Leadership Act (S.1462) to proposals that place an economy-wide cap on greenhouse gas emissions, such as the American Power Act. This memo seeks to compare the major provisions included in the full range of legislative proposals.