Institutional multilingualism is most often associated with large intergovernmental institutions such as the European Union and the United Nations. Multilingualism in non-governmental organisations (NGOs), however, has remained invisible to a large extent. Yet these organisations have been identified as very powerful in world politics in the globalised 21st century. Like international governmental organisations (IGOs), they operate across linguistic and language borders. This raises the questions if NGOs actually use language and translation in the same way as IGOs. This article examines Amnesty International as a case study and explores what official multilingualism means for this organisation, how it is reflected in its language policy, and how it is put into practice. By gaining insight into the particular case of Amnesty International, this article aims to make a contribution to institutional translation studies.