This chapter introduces a new, more systematic classification of institutions of international society: ideological institutions (nationalism, multilateralism, cosmopolitanism, Confucianism), constitutive institutions (sovereignty, international law, global economy), instrumental institutions (diplomacy, power balancing, investiture and tribute system) and mechanical ones (international regimes and organisations). How the different ideological institutions, nationalism and multilateralism – and in the past – Confucianism, have shaped the same three constitutive institutions in very different ways is shown for Europe and Northeast Asia. This approach convincingly explains historical institutional pathways of both regions and how they deal with governance challenges.