The need to decrease concentrations of carbon dioxide and other greenhouse gases (GHGs) in Earth's atmosphere has been identified as one of the most pressing modern-day environmental issues. Agriculture, in addition to being affected by the climate, contributes to climate change through its exchanges of GHGs with the atmosphere. This report provides up-to-date information on the science of carbon sequestration and GHG mitigation for various sectors of U.S. agriculture, including logistical and economic considerations for implementing practices designed to decrease GHG emissions from agriculture. The report draws on elements of the related 2004 CAST Task Force Report, Climate Change and Greenhouse Gas Mitigation: Challenges and Opportunities for Agriculture.