A report published jointly by the Food & Agriculture Organization of the United Nations and the Water for Food Global Institute at the University of Nebraska reviews current methods for yield gap analysis, clarifying definitions and techniques to measure and model actual, attainable and potential yield at different scales in space and time and using case studies to illustrate different approaches. The report builds on the activities of FAO and the institute to develop tools and knowledge delivery systems to better inform and guide policymakers in managing water and agriculture.