Global citizenship education (GCE) has recently emerged as a dynamic approach to education capturing the interest of various stakeholders, including academics, educators and international organisations worldwide. In an increasingly interconnected and interdependent world, GCE is seen as a transformative pedagogy that can empower learners to resolve growing global challenges, building a more just and sustainable world. This study explores how GCE is “transferred, translated and transformed” (Cowen, 2009a; 2009b; 2006) into contemporary national education policy and practice, through a comparison of experience between Greece and Sweden. Based on a qualitative research approach, the study first examines the discourse of international organisations, such as UNESCO, the European Union and Oxfam, in order to better understand efforts to promote GCE and its implications for teaching and learning. National education curricula on citizenship-related subjects are then analysed to identify how they address GCE, while a third level of analysis involves exploring how primary school teachers and students perceive and implement the particular concept. To this end, document analysis, interviews and focus groups have been employed as methods to gather relevant data. The findings of the study indicate that international organisations have developed a powerful GCE discourse, elements of which can be seen in national education policy and school practice, yet with different emphasis between countries as a result of diverse socio-economic, political and historical contexts. In Greece, the focus on ethnocentrism and Europeanism hinders the effective delivery of GCE, whereas in Sweden, the strong commitment to human rights and internationalism allows to integrate the concept in school practice. The predominant form of global citizenship promoted in both countries is moral cosmopolitan, while critical and postcolonial approaches to the concept do not appear to have been recognised or implemented in practice. Considering all three phases of shape-shifting educational ideas, as defined by Cowen (2006), the study concludes that although policy support for GCE is evident in international and national policy discourse, actual implementation in schools is weak.