Technical Abstract: The environmental footprints of beef produced at the U.S. Meat Animal Research Center (MARC) in Clay Center, Nebraska were determined through a simulation of their production system. Relevant information for MARC operations was gathered and used to establish parameters representing their production system with the Integrated Farm System Model. The MARC farm, cow-calf and feedlot operations were each simulated over 25 years of recent historical weather to evaluate performance, environmental impact and economics. The farm operation included 2,072 acres of alfalfa and 2,865 acres of corn to produce feed predominately for the beef herd of 5,500 cows, 1200 replacement heifers and 3,720 cattle finished per year. Spring and fall cow calf herds were fed on 24,000 acres of pastureland supplemented through the winter with hay and silage produced by the farm operation. Feedlot cattle were backgrounded three months on hay and silage and finished over 7 months on a diet high in corn grain and wet distiller’s grain. Model simulated predictions for weather year 2011 agreed well with actual records for feed production and use, energy use and production costs. A 25-year simulation of their current production system gave a carbon footprint of 11 lb of carbon dioxide equivalent units per lb of live weight sold, and the energy required to produce that beef (energy footprint) was 11,200 Btu/lb. The total water required (water footprint) was 2,550 gallon/lb of live weight sold, and the water footprint excluding that obtained through precipitation was 340 gallon/lb. The simulated total cost of producing their beef was approximately $1.00/lb of live weight sold, which agreed with their production records. Simulations are being developed for 2005 and 1970 to determine how the environmental footprints have changed over time.