In recent decades, historical studies of public policies on children and youth have paid scant attention to the transnational dimension which may have governed their emergence. This article focuses on the transnational perspective of social and cultural history, to understand the role that international organizations have played in disseminating child welfare measures. It focuses on the workings of the Child Welfare Committee (CWC) of the League of Nations, and the internal transactions and mechanisms that enabled it to play a central role in defending the cause of children between the world wars. Analysis of the committee's work reveals the dissemination mechanisms in contemporary social policy, and the role played by international governmental and private organizations. The article also describes the emergence of the first international networks devoted to child welfare in the late 1800s, the circumstances around the CWC's creation, and the mechanisms through which the League of Nations became a collegial centre of expertise on both child welfare and its related policies.