This volume joins the full text of Laudato Si' with reflections by Sean McDonagh, one of the foremost Catholic proponents of ecological awareness. Aside from reviewing the history of Catholic teaching and the environment, he elaborates on several of the specific themes in the encyclical -- climate change, biodiversity, water scarcity, the threats to the ocean, and the crisis of food. He concludes with prescriptions about what must be done to turn the vision of Pope Francis into a program of effective action. Each of us has a role to play. As Pope Francis observes, "All it takes is one good person to restore hope."