Ensuring sustainable food systems requires vastly reducing its environmental and health costs while making healthy and sustainable food affordable to all. In current food systems many of the costs of harmful foods and benefits of healthful foods are externalized, i.e. are not reflected in market prices and therefore not in decision making of actors in food value chains. Solving the externality problems means to determine current costs of externalities and redefine food prices (true pricing) to internalize them in daily practice. Policy makers, businesses and other actors in the food system, lack sufficient information and knowledge to internalize externalities to achieve a sustainable food system. FOODCoST responds to this challenge by designing a roadmap for effective and sustainable strategies to assess and internalise food externalities. FOODCoST provides approaches and databases to measure and value positive and negative externalities, proposing a game-changing and harmonised approach to calculate the value of climate, biodiversity, environmental, social and health externalities along the food value chain based on economic cost principles. FOODCoST provides an analytical toolbox to experiment, analyse, and navigate the internalisation of externalities through policies and business strategies providing tools and guidance to policy makers and businesses to assess the sustainability impact of their internalisation actions. FOODCoST emphasises the diversity of challenges of true pricing in different value chains and countries and regions, and cocreates, tests and validates the valuation and internalisation approaches in 11 diverse case studies enabling to test, validate and enrich the approaches in order to transit towards a sustainable food system. The project will be based on a multi-actor approach that will ensure a continuous dialogue with all relevant actors across the whole food system (land and sea).