Humanity has been passing through stages of collective growth towards integration and unity. Our current collective crises–climate change, financial upheavals, proliferation of nuclear weapons, gross human rights atrocities, mismanagement of critical natural resources–manifest our passage through a turbulent adolescence. This book analyzes why and how humanity can take the next step towards maturity by establishing collective decision-making institutions that can evolve into a world federation of nation-states. Only then will we have a truly peaceful world.