The Comprehensive Assessment of Water Management in Agriculture is a critical evaluation of the benefits, costs, and impacts of the past 50 years of water development, the water management challenges communities face today, and the solutions people have developed around the world. It is a multi-institute process aimed at assessing the current state of knowledge and stimulating ideas on how to manage water resources to meet the growing needs for agricultural products, to help reduce poverty and food insecurity, and to contribute to environmental sustainability. The findings will enable better investment and management decisions in water and agriculture in the near future by considering their impact over the next 50 years.