This article lays the foundations for a sociology of cosmopolitan harm conv
entions which protect the vulnerable everywhere from avoidable suffering an
d distress. It builds on the study of international society associated with
the "English School" and seeks to develop its account of how states cooper
ate to reduce harm in their external relations. The English School argues t
hat the principal harm conventions in international society are designed to
maintain order between states. There is only limited agreement about how i
nternational order should act to prevent harm to individuals and non-sovere
ign associations. Several international legal conventions do outlaw harm wh
ich is justified in terms of the superiority of some cultures or races over
others, and perhaps modern international society is making progress beyond
earlier forms of world political organization by insisting that transnatio
nal, or cross-border, harm should be a central moral concern for the world
political system as a whole. But to do so, it needs to transcend the forms
of harm that particular groups inflict on others and the more diffuse types
of harm which are caused by global capitalism and industrialization. A mor
al commitment to new forms of domestic and international political communit
y which have this ambition lies at the heart of a sociology of cosmopolitan
harm conventions with an emancipatory intent.