Cosmopolitanism is the idea of humanity as a single community or polis. Beyond particularities, all human beings (and in some versions of cosmopolitanism certain non-humans) are part of a community, and have responsibilities, rights and the power to decide on a common future. Ideas of cosmopolitan vary from the purely moral to cultural, social, legal, institutional, political, educational and economic cosmopolitanism, or combine some or all of these facets. All of these different perspectives try to establish the basis necessary to create a true cosmopolitanism. This book provides an introduction to the ideality and reality of cosmopolitanism, presenting it in genesis and giving a point of departure to students and readers of cosmopolitanism from which to analyse its various contemporary versions and proposals, providing an additional tool for their thinking and judgments in the face of a huge amount of literature today. It also offers a sense of emergency to those matters, requiring a prompt legal, political and economic response, for the continuing existence of the planet and for cosmopolitanism to continue as a viable proposal for humanity. As such, this volume will, ultimately, provoke the reader into a new spirit and action, that of cosmopolitanism.