This chapter reports upon a European Union (EU) funded project that aimed to improve the quality of global citizenship education (GCE) taking place in schools across five countries and to increase the number of teachers actively engaging with GCE through creating and testing methodologies for measuring impact on attitudes and values. The project builds upon over ten years of work by Reading International Solidarity Centre (RISC), a UK Development Education Centre (DEC), supporting teachers to identify which of their teaching interventions have the greatest positive impact on young peoples’ attitudes and actions.