In this report, agriculture is interpreted in the narrower sense of crops and livestock. Fisheries and aquaculture were treated in a dedicated HLPE report in 2014, while forestry will be covered in a report to be released in 2017. Livestock is used to designate domesticated terrestrial animals raised for food production. Given the breadth of the topic, and as reflected in its title, this report focuses on the livestock sector because it is a powerful engine for the development of the agriculture and food sector, a driver of major economic, social and environmental changes in food systems worldwide, and a uniquely powerful entry point for understanding the issues around sustainable agricultural development as a whole. Livestock production is central to food systems’ development and is a particularly dynamic and complex agricultural subsector, with implications for animal-feed demand, for market concentration in agricultural supply chains, for the intensification of production at the farm level, for farm income, land use, and for nutrition and health. Livestock has often set the speed of change in agriculture in recent decades. Livestock is strongly linked to the feed crop sector, generates co-products including manure and draught power, and in many countries acts as a store of wealth and a safety net. It is integral to the traditional practices, values and landscapes of many communities across the world. Livestock has significant effects on the environment, both positive and negative, particularly when indirect land-use changes and feed crop production effects are taken into account. As highlighted by numerous contributions to the electronic consultation on the V0 Draft of the report, the focus on livestock, while legitimate as a way to illustrate the complexity of SAD, should not hide the critical importance of the crop sectors. The common approach proposed in this report, to define pathways to SAD in different livestock systems, and the attention paid to crop–livestock interactions can also be used for the wider agriculture sector. Changes in consumption and dietary patterns will be critical in shaping SAD for FSN. Those subjects will be looked at in a specific HLPE report on Nutrition and food systems to be published in 2017. Taken together, these two reports will provide a significant contribution to informing debates on sustainable food systems along the food chain from production to consumption. The report offers policy-makers and other stakeholders a framework to design and implement feasible options of sustainability pathways for agricultural development. It will hopefully contribute to sustainable food systems and to FSN for all, and more broadly to the 2030 Agenda, now and in the future.