On 25 June 2013, President Obama announced a national plan to reduce emissions of carbon dioxide (CO2) and other greenhouse gases (GHG), as well as to encourage adaptation to expected climate change. The President affirmed his commitment to his 2009 policy pledge to reduce U.S. GHG emissions by 17% below 2005 levels by 2020 if all other major economies agreed to limit their emissions as well. In 2011, the United States' gross GHG emissions were approximately 7% below their 2005 levels. The President stated a willingness to work with Congress toward enacting a bipartisan, market-based scheme to reduce GHG emissions. The President's Climate Action Plan lays out a series of measures in three categories: 1) cut carbon pollution in America, 2) prepare the United States for the impacts of climate change and 3) lead international efforts to address global climate change. Many measures included in the Climate Action Plan have been underway. The plan specifies few timelines or metrics for evaluating progress of individual measures beyond national aggregate or sectoral GHG emissions or energy efficiency. The centrepiece of the President's announcement arguably is a Presidential Memorandum, also issued June 25, that directs EPA to issue two types of rules to curtail carbon dioxide emissions from new and existing power plants before the end of his term. This book provides an overview of President Obama's Climate Action Plan, with a focus on key elements and analyses.