The aim of this paper is to provide policy-makers with a helpful overview of the technical and economic aspects of water use in agriculture, with particular emphasis on crop and livestock production. Through 2050, in many countries, agriculture will remain an important determinant of economic growth, poverty reduction, and food security, even as, over time, the proportion of agricultural revenue in national gross income declines. Water use in agriculture will remain substantial, irrigated areas will expand and competition for water will increase in all sectors. Most likely, overall supplies of land and water will be sufficient to achieve global food production goals in 2050; although poverty and food insecurity will remain pressing challenges in several regions and countries. Thus, the focus of this report is on the regional and national aspects of food security.