Sheep production is a long-standing agricultural practice across the world, but the impact of our food production systems on the environment is receiving increasing attention, in particular with regards to climate change. To preserve the industry for future generations, sheep production systems must improve practices to reduce environmental impacts while considering socio-economic factors. This book chapter aims to provide an exploration of sustainability issues in sheep farming, summarising a key measurement method (LCA) while exploring challenges and prospects for improvement. Sustainability issues and what a sustainable sheep industry requires are discussed, alongside factors that limit application of LCA to sheep systems. This includes inherent uncertainty in modelling, for example variation in input data and methodology choices. A summary of recent LCA results is given and the impact of making these measurements on assessment of different mitigation strategies is discussed. The chapter concludes with reflections on the requirements for future research.