Problem: Most research on planning to mitigate climate change has focused on reducing CO2 emissions from coal-fıred power plants or the transportation sector. The contribution of forests to lowering net CO2 emissions has largely been overlooked. U.S. forests already offset about one eighth of the nation's annual CO2 emissions and have the potential to offset more, all at a relatively low cost. It will not be easy to integrate forest carbon sequestration into a cap-and-trade program to reduce net CO2 emissions, however. Purpose: I explore what forest land use planning, forestry management practices, and land preservation strategies would be required to integrate forest carbon sequestration into a cap-and- trade program, and explain the role planning and planners can play in promoting forest carbon sequestration. Methods: The Regional Greenhouse Gas Initiative is a 10-state cap-and-trade program to reduce greenhouse gas emissions from coal-fıred power plants in the northeastern United States. It provides a case study of how forest carbon sequestration can be included in a cap-and-trade program. Meanwhile, California has devised certifiable carbon credits from forestland. I analyze both approaches and generalize from them. Results and conclusions: To promote forest carbon sequestration through a cap-and-trade program will require ensuring the permanence of CO2 reductions, minimizing leakage from forestland conversion, and obtaining prices for carbon offsets that are high enough to induce forestland owners to participate in the program and offer them for sale. The capital needed to purchase and monitor permanent forest conservation easements as well as to provide a stream of annual income for timberland owners may require a national system of carbon credits. Ideally, the easements would be set up in advance through investments by government or non-profıts, so that landowners will be ready to sell credits when they are demanded. Takeaway for practice: A cap-and-trade system could be a cost-effective way to lower net CO2 emissions if it included certifiable, trade-able credits from forestland preservation and management, and if the price of carbon credits were high enough to induce forest landowners to offer credits. To promote forest carbon sequestration, planners in rural areas should work with the local, state, and federal governments and non-profıt land trusts to zone forestland at low densities, to preserve forest land through acquiring conservation easements, and to fashion forest management plans that ensure long cycles of timber harvesting. Planners in metropolitan areas should promote tree planting and tree retention ordinances to protect, expand, and manage urban forests to absorb greenhouse gases.