Problem: America continues to lose its highest quality farmland at an alarming rate. Of the 10.9 million acres of farmland lost to development from 2001 to 2016, 4.4 million acres, or 40%, were "Nationally Significant" because of their high productivity, versatility, and resiliency to climatic changes (Freedgood et al., 2020). High quality agricultural land is one of the nation's most important natural resources. Its conversion to development represents an irreversible loss of our nation's capacity to grow food and other ecosystem services associated with agricultural land, as well as attendant economic and rural community effects. It is not possible to protect all farmland from development, but this proposal proceeds from the assumption that we should try to protect the highest priority farmland.Knowledge Gap: Currently, decisions about where to protect farmland typically are made opportunistically (e.g. siting an easement where there is a willing farmer), or according to socio-political boundaries (e.g. zoning according to a city-limit). A more systematic approach to protecting high-priority farmland is needed. The first step is to develop a standard definition of how to measure "value" in terms of agricultural land. An "ecosystem services'' (ES) approach provides a framework for measuring multiple benefits that society receives from viable agricultural landscapes (Freedgood et al., 2020; Qiu & Turner, 2013). For example, crop productivity is important, but so are factors such as climate resilience, specialty crop production, or important non-food benefits that agricultural lands provide, such as cultural heritage, rural community well-being or species habitat (Narducci et al., 2019; Slemp et al., 2012; Quintas-Soriano et al., 2020).Additional social and economic concerns must also be considered when prioritizing farmland protection (Bunce, 1998). For instance, individuals and communities are not equally accepting of land use policies or interventions, and people at multiple levels (e.g., individual farmers, county planners, state legislators) must support farmland protection strategies for them to be effective. In addition, development pressure is an important consideration when investing in agricultural protection. For example, there is likely not a need to place an easement on farmland in areas where development is not a threat. Understanding the range of social and economic factors influencing farmland protection is essential for effective prioritization strategies.Project Objectives: We propose to develop a systematic and data-driven approach to prioritizing where and how to protect farmland (Fig. 1). Our study area is the Snake River Plain agricultural region of Idaho, which is both a nationally and internationally important agricultural production region, and a hotspot of human population growth. Our specific objectives are:1. Map a suite of ES across the entire Snake River Plain under current and projected land use scenarios, and measure the trade-offs and synergies among ES associated with farmland loss.2. Develop a Farmland Protection Planning (FPP) approach that uses optimization algorithms to identify priority areas for protection based on ES, land productivity, climate resiliency, and development pressures.3. Examine social factors influencing farmland protection using qualitative social science research methods.4. Create a "Farmland Protection Planning Handbook" for practitioners that integrates the spatial maps of prioritized farmland with insights gained from the social science.