Congress is considering proposals for market-based programs to limit greenhouse gas emissions. Many proposals involve creating a cap-and-trade program, in which an overall emissions cap is set and entities covered by the program must hold tradable permits-or-"allowances"-to cover their emissions. According to the Congressional Budget Office (CBO), the value of these allowances could total $300 billion annually by 2020. The government could either sell the allowances, give them away for free, or some combination of the two. This book examines the implications of different methods for selling allowances, given available information and the experiences of selected programs with regard to climate change policy options.