Market-based environmental policy analysis requires taking into account all the institutional factors necessary for the market to function optimally, as well as the social forces that shape a final policy design. This book sheds light on the institutional history of the emissions trading concept as it has evolved across different contexts. Diplomats, policy experts, academics, and the carbon trading industry currently have a monopoly of knowledge about the intricacies of developing and implementing emission trading systems (ETS) for environmental control. This book seeks to weaken that monopoly. It makes accessible the policy design and practical implementation aspects of a key tool for fighting climate change. Blas Perez Henriquez analyzes past market-based environmental programs to extract lesions for the future of ETS. He follows the development of the emissions trading concept as it evolved in the United States and was later applied in the multinational European Emissions Trading System and in subnational programs in the United States such as the Regional Greenhouse Gas Initiative (REGI). This ex-post evaluation of an ETS as it evolves in real time in the real world provides a valuable supplement to what is already known from theoretical arguments and simulation studies about the advantages and disadvantages of the market strategy. Political cycles and political debate over the use of markets for environmental control make any form of climate policy extremely contentious. Henriquez argues that, despite ideological disagreements, the ETS approach, or, more popularly, 'cap-and-trade' policy design, remains the best hope for a cost-effective policy to reduce GHG emissions around the world.