Technical Abstract: Switchgrass (Panicum virgatum L.) is a C4 grass native to the North American tallgrass prairies, which historically extended from Mexico to Canada. It is the model perennial warm-season grass for biomass energy. USDA-ARS in Lincoln, NE has studied switchgrass continuously since 1936. Plot-scale research has been conducted in the Great Plains and Midwest on switchgrass establishment, fertility requirements, and response to harvest date. Switchgrass production parameters such as economics, net energy, carbon sequestration, temporal and spatial biomass variation, and harvest and storage management have been evaluated at the field-scale on marginal land on 10 farms in the Great Plains. Switchgrass was produced for an average farm gate cost of $60 per US ton, resulting in an average feedstock cost of $0.64/US gallon ethanol. Switchgrass produced 13 times more energy as ethanol than would be required as energy from petroleum and produced 540% more renewable than non-renewable energy consumed when properly managed. After five production years on four Nebraska farms, soil organic carbon was sequestered at a rate of 1.3 US tons per acre per year in the top 4 feet of soil. Using higher yielding bioenergy-specific cultivars will increase biomass production with similar inputs. Increasing biomass per unit input with improved agronomics and genetics will enhance the economics and energetics of biofuel production.