This chapter examines how the International Bureau of Education (IBE) in Geneva repositioned itself between 1929 and 1939 to become a government-based intergovernmental organization, shifting away from its earlier links to reformist educational movements. The study is based primarily on IBE Archives (A-BIE) and the Jean-Jacques Rousseau Institute Archives (AIJJR), including internal correspondence, minutes, and administrative reports. Key actors such as Jean Piaget, Pedro Rosselló, and Marie Butts reorganized the Secretariat and launched the International Conferences on Public Instruction (CIIP) from 1934 onward. The analysis draws on historical sociology of institutions, transnational history, and the history of educational expertise. It highlights the negotiation between claimed scientific neutrality and political pressures during the interwar years.