With few exceptions, the nations of the Middle East and North Africa (MENA) have already reached or are fast approaching the limits of their indigenous water supplies. Some forces, such as higher prices for water, increased efficiency, and institutions for bi- or tri-national management of shared water bodies, can (and likely will) mitigate their problems. However, others, such as climate change, ongoing conflict, and higher populations and incomes, will exacerbate them. Sustainable water use in the region requires a shift from the historic emphasis on increasing water supply to options for reducing and reallocating water demand. Technology is available, and the economics are favorable. What is lacking are innovative institutions for, and better management of, the limited freshwater resources. Because so much of the region's fresh water is used for irrigation, and because agriculture is so embedded in regional societies, the most difficult part of the shift will depend on a gradual return to predominantly rainfed farming methods.