This article considers the role of the Scandinavian states in the establishment of the
Permanent Court of International Justice (PCIJ), by analysing the interplay between
their legal-diplomatic praxis and five different diplomatic arenas between 1917 and
1920. The Scandinavian role in the establishment of the PCIJ constituted a new way to
influence international politics in an emerging institutionalized multilateral setting. It was no accident that Scandinavian diplomatic coordination came in the field of international law: already before 1914, they promoted international law as central to a new more peaceful organisation of the international system; during the war and immediately after they forged a common approach. Beyond the intentions of three states, however, we argue that the qualities and sequencing of the diplomatic arenas mattered greatly in shaping the role of the Scandinavians and the establishment of the PCIJ.