Growing demand for food in the coming decades asks for an substantial increase of the current global crop production. Given limited land suitable for crop production achieving highest possible yields on existing farm land is the only feasible solution to ensure food security while protecting carbon- and biodiversity-rich rainforests, wetlands, and grasslands. Quantifying the size of current exploitable yield gaps — the difference between current farm yields and yield potential — provides the basis for identifying regions best suited for agricultural intensification and helps to prioritize investments in agricultural research and development. This symposium will focus on opportunities to improve methods for quantifying yield gaps at local to global scales, and how to use and interpret yield gap assessment data. Two half-day sessions are proposed. The first half-day session will provide a general overview about the needs for yield gap assessments and recent advances in developed methods to estimate them, including choice of weather, soil and management data and crop models, validation of crop yield potential estimates, and up-scaling from local to national levels. The second half-day session will focus on case studies of yield gap analysis from data-rich regions such as USA and Europe, but also from data-poor regions such as Africa and Asia, encompassing cropping systems across a wide range of climatic, technological, and social conditions. The session will end with a summary presentation about progress in methods used for yield gap assessments and how to interpret the results that emerge from earlier presentations, followed by an open discussion.