Much ink has been spent on the question in which direction NATO should develop in the future. Although a consensus among its members is still lacking, this article argues that NATO should open its membership to all consolidated democracies and hence turn into a global organisation. This thesis is supported by historical evidence on the nature of international organisations and the lack of a thorough rearrangement of international organisations following the end of the Cold War. It outlines a theoretical formula to guide a global enlargement in practical terms, calling to invite those countries that would add to NATO’s capabilities without adding a potential in new conflicts