To Nicolas, Raphaëla nd Mila the Swiss National ScienceF oundation (SNSF).Iw ould liket ot hank Sandrine Kott,m yt hesis supervisor,whose constant support,d ynamism, openness, frankness, experience and wise advice wered ecisive factors in the realisation of this research. Iwould also like to thank Ludovic Tournès, who wasanattentive and demanding co-director,whose remarks and advice made it possible to further improvemyresearch. Ialso wish to expressmy gratitude for the time they have givent om e.Iwould liketothank the ILO archivists, Remo Becci, Renée Berthon and Jacques Rodriguez. Ia mg rateful for their warmw elcome, their advice and for the ideas we exchanged between two boxeso fa rchival files. Iw ould also like to thank the civil servants of the ILO DOSCOM Service whom Ihavehad the pleasure of workingwith duringthese years of research. Iextend my thanks to Jacques Oberson for his welcome to the archivesofthe League of Nations,aswell as the UN archivists in Geneva; Romain Ledauphin of the UN archivesinNew York and Mary Ann Quinn of the Rockefeller Foundation archivesi nN ew York. Iw ould also like to thank Pierre Roehrich for sharing his familyhistory with me and allowing me to consulth is grandfather Maurice Thudichum'sa rchives.