This book tells the story of a largely forgotten enterprise: that of the International Scientific Committee on Price History. If this endeavour can nevertheless still be of interest today, it is not only because failures offer insights into social dynamics as well as successes do ; nor is it solely because we find, gathered around this failed enquiry, a slew of very famous names, and names indeed which one would not expect to stumble upon in this context – there is Beveridge and Kautsky, Bloch and Malinowski. First and foremost, it is because the object of this enquiry offers a rare opportunity to bridge the divide between national scientific traditions as well as between disciplines – such as history and economy, or epistemology and the sociology of scientific knowledge. Thus, the initially narrow scope of this study opens up to a vast field of enquiry, as the object of this study shifts to determining how a particular class of objects – those deemed scientific – are produced, and how epistemological, theoretical and institutional issues interact in this process. Indeed, the conversion of past prices (as they appear in the archives) into historical prices taken as scientific facts, raises diverse and crucial questions : on the respective standing of social and natural sciences, about monetarism, or on the transition from the academic field of the Humboldtian scholar to that of big science. Viewed through the prism of this particular case, these issues will appear in a new light for the simple reason that, in the case at hand, fields of enquiry which are ordinarily examined independently are found to be tightly interrelated.