Why is there no reactionary international theory? International relations has long drawn on a range of traditions in political thought. However, no current, or even recent, major school of international-relations theory embraces reactionary doctrine. This is more surprising than some might assume. Reaction was once common in the field and is now increasingly common in world politics. In this note, we define reaction and show that no active and influential school of international-relations theory falls within its ideological domain. Nonetheless, reactionary ideas once deeply shaped the field. We identify two distinct kinds of reactionary international politics and illustrate them empirically. We argue that the current lack of reactionary international relations undermines the field's ability to make sense both of its own history and of reactionary practice. Finally, we offer some preliminary thoughts about why reactionary ideas hold little sway in contemporary international-relations theory.