Founded in 1919 under the Treaty of Versailles as part of the League ofNations’ system, the ILO is still today the main organization responsible forthe international organization of work and the improvement of workingconditions in the world. Widely recognized for its efforts in buildinginternational labour standards, the ILO remains little studied by developmentspecialists and historians. This book intends to fill this gap and traces thehistory of international development and its early pioneers, through ananalysis of the activities of the International Labour Office, the Secretariat ofthe International Labour Organization, between 1930 and 1946. In this book,development is used as a key to questioning the ILO's place and function inthe expanding inter-war world. The development practices and discoursesthat emerged in the 1930s were mainly intended to support the ILO'suniversalization strategy, which was made necessary by the events that shookEurope at the time. Development discourses and practices were also part ofthe "esprit du temps", as they were closely linked to the affirmation of theplanist and rationalist ideas of the 1930s. However, development for the ILOwas not reduced to a project of economic modernization, but was seen as atool for social engineering, as evidenced by the ILO's missions of technicalassistance, organized since 1930. The analysis of the expertise work makes itpossible to highlight the logics that prevailed in technical assistance, whichwas more in line with institutional objectives, than with the dissemination ofa genuine expertise. This book therefore hopes to bring new insight on thehistory of internationalism, and international organizations during the inter-war period and the Second World War, as well as on the role of the ILO in the history of international development thinking and practices.