As ruminants, beef cattle are converters of human-inedible biomass into edible, high quality protein. The environmental costs of their role as upcyclers are their direct and indirect contribution to environmental emissions which negatively affect air and water quality, and their consumption of finite natural resources. Grass-fed beef has been touted in recent years as an environmentally friendly alternative to conventionally produced beef due to its exclusive reliance on forages, which are human-inedible feedstuffs. The purpose of this study was to characterize grass-fed beef production systems in the Northeast U.S., and to evaluate them for their intensities in greenhouse gas emission, reactive nitrogen loss, blue water consumption, and fossil energy consumption, and their cost of production. To this end, grass-fed beef producers across the Northeast were surveyed and interviewed about their land, animal, and feed management practices. Representative production systems were defined based upon similarities in management practices and their location within the region according to the USDA Plant Hardiness Zone map. Once categorized, systems were analyzed for differences in herd composition, animal performance, land management, and animal productivity defined as the total market weight produced divided by either the on-farm or total land use. Most farms managed cattle from birth through finishing on the same farm. Animal productivity per hectare was up to two and a half times greater in warmer zones than in cooler zones, likely attributable to grazing seasons that were 1 to 4.5 months longer and stocking rates that were 44 to 60% denser, both of which are a reflection of greater forage yield in warmer zones. Herd composition and animal performance were similar across zones. Farms were further classified according to their status as either feed sufficient (all feeds required to support the herd and finish market cattle were produced on the farm) or feed importing (all feeds aside from pasture required to support the herd and finish market cattle were purchased). Feed importing farms were about half the size of feed sufficient farms, but used about 37% more land per animal, resulting in 60% lower productivity per hectare. These results translated into 38% greater reactive nitrogen loss (172 to 203 and 252 to 269 g N/kg live-weight for feed sufficient, and feed importing farms, respectively) and 78% greater fossil energy consumption (22 to 24 and 40 to 56 MJ/kg live-weight for feed sufficient, and feed importing farms, respectively) intensities (footprints) for feed importing farms than feed sufficient farms within zones. Differences in GHG emissions (18 to 30 and 20 to 30 kg CO2-equivalents/kg live-weight for feed sufficient, and feed importing farms, respectively) and blue water consumption (59 to 72 and 57 to 69 L H2O/kg live-weight for feed sufficient, and feed importing farms, respectively) intensities across farm types were negligible within zones. Greenhouse gas emission intensities differed more across zones due to differences in underlying soil texture and climate. Cost of production per hectare was 1.5 times greater for feed sufficient farms than for feed importing farms. Overall, feed sufficient farms were more eco-efficient than feed importing farms, as they had both lower environmental impact intensities and cost of production. Measures to improve the eco-efficiency of either system are difficult, as two major underlying drivers of these differences are underlying soil textures and farm size. Irrespective of production system, managing nitrogen dynamics on these farms should be a priority. Nitrogen losses via leaching through the soil profile, nitrification, and denitrification processes were significant contributors to both the reactive nitrogen loss and greenhouse gas emission intensities. Controlling these losses should lead to improvements in eco-efficiency, provided there are not tradeoffs between impact categories or increases in per-unit cost of production without corresponding increases in prices received. Future research should explore the potential for manipulating protein to carbohydrate ratios in pasture via use of plant diversification, incorporation of annual forages in cropping systems, and strategic supplemental forage feeding to improve the eco-efficiency of Northeast U.S. grass-fed beef systems. In addition, social influences on management practices should be explored in order to develop more targeted interventions for nitrogen management on each farm type, as this likely underlies differences in farm size between the farm types explored in this dissertation.