Can people alive now have duties to future generations, the unborn millions? If so, what do we owe them? What does "justice" mean in an intergenerational context, both between people who will coexist at some point, and between generations that will never overlap? In this book, Axel Gosseries provides a forensic examination of these issues, comparing and analyzing various views about what we owe our successors. He discusses links between justice and sustainability, and looks at the implications of the fact that our successors' preferences are heavily influenced by what we will actually leave them and by the education they receive, He also points to how these theoretical considerations apply to real-life issues, ranging from pension reform and Brexit to biodiversity and the climate crisis. He ends by outlining how intergenerational considerations may translate into institutional design. Anyone grappling with the dilemmas of our obligations to the future, from students and scholars to policy makers and active citizens, will find this an invaluable theoretical and practical guide to this moral and political minefield.