A large proportion of the United Kingdom’s agricultural land is classified as uplands. The majority of this land is used for livestock production,but pasture productivity is often low. This, together with market forcesand changes in support payments for agriculture, mean that cattle numbers in the uplands are declining. A continuation of this trend could compromise beef production and lead to other undesirable impacts such as the spread of invasive species.The red meat sector is also under considerable pressure to reduce its environmental burden.This may bring additional pressures on upland livestock systems.Optimised management of pasture is fundamentally important in maintaining grass quality and quantity, providing sufficient nutrition to ruminants. Improving pasture productivity and grass utilisation could provide numerous benefits such as increasing the length of the grazing season, thereby reducing supplementary feed requirements and decreasing greenhouse gas emissions from agriculture.While many studies have evaluated the effectiveness of pasture improvement methods on increasing pasture productivity, few have focussed on the environmental outcomes in relation to the uplands. An improved understanding of this is important for identifying opportunities to increase production efficiencies on-farm as well as reduce greenhouse gas emissions from upland cattle systems.The overall aim of this thesiswas to determine the effect of alternative pasture and grazing management options in upland cattle systems on production efficiencies, and their respective environmental trade-offs. Firstly, aliterature review (Chapter 2) was conducted whereby I discussedexisting studies, as well as identifiedknowledge gaps in the research. Chapter 3, the first experimental chapter, assessed thecurrent and potential pasture productivity on a typical upland farm in north Wales over a three-yearperiod in order to investigatethe environmental costof various options to increasepasture productivity in the uplands. Pasture productivity was significantly higher following reseeding with a grass variety for marginal land than from current upland permanent pasture. Furthermore, higher nutrient (lime and fertiliser) application in accordance with the Nutrient Management Guide (RB209) resulted in an increase in pasture production. Field operations i.e. reseeding and nutrient application led to increased nitrogen loss via nitrous oxide emissions from the soil. This was particularly evident from rotovated land.In Chapter 4, the efficiency of upland grazing systems for cattle was evaluated by investigating cattle liveweight gain when grazing improved (pasture that received lime and fertiliser application) and unimproved uplands, and nitrous oxide emissions produced from the soil as a trade-off. This was assessed by conducting a field experiment, once again on a typical upland farm in north Wales. In contrast to existing literature, cattle liveweight gain did not differ between grazing treatments, possibly due to not utilising the improved pasture to its full potential. Urine excretion led to significantly higher nitrous oxide emissions from the soil than dung excretion and fertiliser application. In Chapter 5, the findings from previous experimental chapters as well as data from other sourceswere usedto investigate the potential of upland beef production and pasture productivity at the regional level. Furthermore, land use competition for livestock production and afforestation in the future was examined.Many upland areas in Wales identified as potential sites for intensifying beef production overlapped with areas suitable for afforestation, indicating a challenge to accomplish bothin the future.To summarise, this work shows that increasing the efficiency of upland beef production via improved pasture management and sustainable intensification is achievable for upland cattle systems in the future. However, the environmental impact of such mechanisms should be carefully considered to work towards reducing greenhouse gas emissions from agriculture. Further work is required to quantify unmeasured environmental burdens from upland cattle systems.