This book shares scholarly papers from the "Symposium on the Encyclical Pacem in Terris: Its 50th Anniversary and Its Relevance to the 21st Century." Pacem in Terris was the famous 1963 encyclical letter of Blessed Pope John XXIII on "World Peace." Pope John wrote this encyclical letter to the entire world, partly in response to the Cuban Missile Crisis which almost caused a global nuclear war that would have devastated the human family and all species of life on planet Earth. In this letter, John praised the United Nations and the Universal Declaration on Human Rights as important steps toward the creation of a "worldwide public authority" capable of directing nation-states and the world economy toward the common good of all in the human family across planet Earth. He called for global disarmament, global human rights, and global political regulation of the world economy, all on behalf of the global common good. John's call was grounded in the early Christian appropriation of the philosophical vision of the Roman Stoics, who saw the human family as called politically to order itself toward the common good, and thus to reflect the Divine order and beauty revealed in the order and beauty of the Cosmos. The Symposium was held at United Nations Headquarters in New York City on 24 October 2012. It was convened by the Permanent Observer Missions of the Holy See and the Order of Malta in cooperation with "Pax Romana at the UN," which is a project of the New York Office of Pax Romana / Catholic Movement for Intellectual and Cultural Affairs - USA (Cmica-usa). The editors of this volume, Ambassador Francis Dubois and Dr. Josef Klee, are both retired high-level United Nations officials and Co-Directors of the New York Office of Pax Romana Cmica-usa. This Office's "Pax Romana at the UN" project provides organizational support for the work of the Holy See and Pax Romana at United Nations Headquarters in New York City. PACEM IN TERRIS PRESS Publishing Service of Pax Romana Cmica-usa Series on Postmodern Catholic Social Teaching