In 1937, the League of Nations decided to undertake an international inquiry into the status of women and nominated an expert committee to conduct the research. This was the result of interwar feminist agitation for an international equal rights treaty. The work of the experts, however, was interrupted by the beginning of the Second World War. The survey was never completed. Preliminary results nonetheless influenced the international understanding of inequalities between men's and women's status. By analyzing the epistemic premises of the inquiry and its methodological design, this article argues that the League's engagement with the status of women constituted gender as an organizing principle of the global order and recognized women's rights as a legitimate objective of international cooperation. The knowledge production on the nature of gender difference impacted the future framing of gender relations in the activity of international organizations after the Second World War.