Water productivity is defined as the amount of agricultural output per unit of water depleted and can be applied to crops, trees livestock and fish. This chapter reviews challenges and opportunities to improve water productivity in socially equitable ways and in different agro-climatic systems. In areas with ample water supply, developing new and making better use of existing water resources are options, whereas in areas with physical water scarcity, better water harvesting and storage is warranted. However, in all situations it is important to think beyond biophysical technologies and foster enabling institutions to ensure adoption of improved practices and equitable and sustainable benefits. Further improvements can be obtained from reducing post-harvest losses and waster of food in both developing and industrialized economies. Both in irrigated and rainfed cropping systems water productivity can be improved by choosing well-adapted crop types, reducing unproductive water losses, and maintain healthy, vigorously growing crops through optimized water, nutrient, and agronomic management.