Pan-Asianism as a concept is conventionally associated with Japan’s imperialism during the Second World War. Pan-Asianism was not merely a language of hegemony, however, but rather had a more complex role to play in the early twentieth century. As an anti-imperial ideology, Pan-Asianism advanced a normative argument for the emancipation of Asia from Western imperialism and provided an alternative vision of civilization. As an anti-imperial strategy, Pan-Asianism offered Indian nationalist leaders in exile a necessary language to gain international support in favour of their nationalist movement. The ideological and strategic aspects of Pan-Asianism then affected and informed the development of contemporary international law with specific reference to the law of neutrality, the right to self-determination, racial equality, and the Monroe Doctrine. This lecture will shed light on this important yet ignored episode in the historical development of international law.