The idea of “global citizenship” is not new, but new and challenging are the conditions featuring today’s world in which this idea has come again to the fore. Indeed, nation-state citizenship no-longer exhausts the political, legal and social relevance of citizenship, in the face of phenomena such as the development of trade and financial markets, information and communication revolutionary technologies, massive (diasporic) migration flows, in addition to threats and risks for human security all around our globalised world. Starting with the awareness of the complexity of these phenomena, the essay focuses on the idea and ideal of global citizenship, looking at it as a long standing idea, but remaining quite controversial and contested as ever. Some various notions are highlighted, from past to present times, of what can be called a cosmopolitan idea of citizenship, by exploring the main aspects characterising its revival in today’s world, and pointing to a methodological approach which implies and requires a paradigm shift in the understanding of what means to be “global”. This brings about the issue of cultural diversity as the counter-value of the ongoing globalization process. Indeed, globalisation has pushed forward cross-country flows of ideas, knowledge, people, as well as products and services. However, behind an apparent trend to homogenisation of world, counter-effects have also been put into motion, which lead, not without tension and even conflict, to the emergence of new dynamics regarding cultural and ethical values, social norms and lifestyles that affect individual and group identities. Increased mobility coupled in particular with migration flows have brought others very close to us. These “others” no longer live in some distant place, but right in our own town or neighbourhood. It arises from here the challenge of the cultural diversity, within our ever more multi-ethnic, multi-religious and multi-cultural societies. In order to deal with this challenge, European experience may offer some good examples on how to manage diversity as a socio-cultural asset that affects both citizenship and education in a double way: a) the education through citizenship, enhancing the socio-educational value of citizenship as daily practice of living together in community; b) the citizenship through education, enhancing the socio-educational value of the intercultural dialogue at the base of an inclusive social dimension of citizenry. Ultimately, a new concept and practice of citizenship is thus emerging, that goes beyond the closed and exclusionary scheme of citizenship classically understood in terms of nationality (nation-state membership), carrying out the meaning of “global citizenship” as paradigmatic feature of an open and inclusive society in which pluralism, non-discrimination, tolerance, justice, solidarity and equality between women and men prevail, in the interest of peace and security.