This book places Pope Francis's landmark 2015 encyclical Laudato si' at the center of an effort to integrate the ethics of migration and ecological devastation. These issues represent two of the great planetary challenges of our time. They are also deeply connected and likely to get worse in the coming decades. As addressed to these issues, the book advances two core arguments. First, Laudato si' and its moral vision of integral ecology represent a culturally creative response to these challenges whose potential for application has not yet been fulfilled. Second, fulfilling the encyclical's promise requires attention to divisions alongside connections. In particular, it requires attention to borders. As sites of power manifested, of families separated, of alienation and friendship, of hope and hopelessness, and of the limits of civil and political order, borders are both a challenge that must be engaged and an opportunity to apply Francis's moral vision in concrete contexts.