This book investigates several dimensions of the concept of cosmopolitanism since Kant. The first of these dimensions is a world vision that considers the construction of a »cosmopolitan self« as a question of justice. The second is the idea that a local political-legal order is fully democratic only if it respects the environment and the human rights of all people of the world, regardless of their citizenship. The third dimension concerns the practice of crossborder associations between individuals, institutionalized or not (cosmopolitics, as Balibar called it). The fourth considers individuals as subjects of international law, as in the case of individual petitions concerning human rights through the European Court of Human Rights and individual responsibility in international criminal law. Finally, the fifth dimension is a form of ecological consciousness based on the relationship between the self and the cosmos, which would imply a profound revision of modern anthropocentric concepts.