The bulk of the literature on transnational governance focuses on the bottom-up emergence of private rules, neglecting top-down processes such as treaty making. This article seeks to remedy this gap, using original archival material to show how a transnational network of experts associated with the International Chamber of Commerce influenced the negotiations of the United Nations Conference on the Recognition and Enforcement of Foreign Arbitral Awards (1958) and its final content. In doing so, this article will analyse the ways in which the complex allegiances developed within the International Chamber of Commerce enabled it to match public authority and private interests in a transnational legal process where states no longer held a monopoly.