Livestock are a critically important component of the food system, although the sector needs a profound transformation to ensure that it contributes to a rapid transition towards sustainable food systems. This chapter reviews and synthesises the evidence available on changes in demand for livestock products in the last few decades, and the multiple socio-economic roles that livestock have around the world. We also describe the nutrition, health, and environmental impacts for which the sector is responsible. We propose eight critical actions for transitioning towards a more sustainable operating space for livestock.