The main theme of this chapter is that Laudato Si’, Pope Francis’s landmark encyclical from 2015, follows in the tradition of other Church documents of the modern era by applying timeless moral principles to particular social and economic challenges of the day—in this case, the challenge of sustainable development. It argues that Pope Francis offers a cutting-edge analysis of the grave and urgent social and environment crisis that threatens human flourishing in the world today, which in turn calls for a firm and timely moral response centered on the achievement of the internationally-agreed Paris Agreement on Climate Change and UN Sustainable Development Goals. And this agenda is the responsibility of all levels of the global community—supranational, domestic, business, individual, civil society, and religious communities. Faced with such challenges, there can be no excuse for inertia, indifference, or the elevation of short-term financial interests over the global common good.