The policy brief has several key messages: Crop diversification can support a transition towards more sustainable agri-food systems, mitigate climate change and help achieve the Sustainable Development Goals; Current national and European agri-food systems are still very much centred on dominant crops and associated long value chains; Crop diversification is hindered by barriers throughout the agri-food system. Such barriers should be removed through systems approaches, which take the whole system into account; Collaboration, innovation and learning among actors are key factors to scale out crop diversification; It is necessary to combine various diversification strategies that are adapted to local conditions and needs, and which evolve over time; Systems approaches and decision-support tools are needed to support actors along crop diversification pathways.