This book calls for a reappraisal of liberalism in international relations theory. Based on the first comprehensive analysis of the ideas on international relations by David Hume, Ludwig von Mises and Friedrich Hayek and a new perspective on Adam Smith and international relations, the analysis shows that classical liberalism differs substantially from other forms of liberalism. The book shows that classical liberalism differs sharply from established forms of liberalism in international relations theory, especially when it comes to the appreciation of the role of power in world politics.