This report outlines various options for containing costs under a cap-and-trade program to reduce greenhouse gas (GHG) emissions. Although cap and trade is generally considered a more cost-effective approach than traditional regulation, excessive allowance prices are a concern, particularly in the early years of a program when some low carbon technologies are not likely to be commercially available. High allowance prices could mean high compliance costs for regulated firms and high energy prices for consumers. A number of the design elements of a cap-and-trade policy