An ecologically sustainable society cannot be achieved without citizens who possess the virtues and values that will foster it, and who believe that individual actions can indeed make a difference. Eco-Republic draws on ancient Greek thought–and Plato\’s Republic in particular–to put forward a new vision of citizenship that can make such a society a reality. Melissa Lane develops a model of a society whose health and sustainability depend on all its citizens recognizing a shared standard of value and shaping their personal goals and habits accordingly. Bringing together the moral and political ideas of the ancients with the latest social and psychological theory, Lane illuminates the individual\’s vital role in social change, and articulates new ways of understanding what is harmful and what is valuable, what is a benefit and what is a cost, and what the relationship between public and private well-being ought to be.