In this book, I have tried to make sense of legitimacy at the international level, especially in relation to international law. I have paid a lot of attention to international law, in particular aligned with the demands of legitimacy and justice. But international law is only one aspect of the forces and the ecosystem that shape international order. Therefore, alone it cannot engineer the change that the international system requires today. This change has to be part of a more comprehensive approach. Here is not the place to offer a full account of the areas on which research could concentrate in the future to further encourage justice and legitimacy at the international level. However, it is worthwhile to present a general overview of these areas. In particular, three domains offer a possible road map for facilitating a constructive path forward: globalization, emotions and passions in social life, and the geopolitics of tomorrow.