Introduced in 1894 as a treatment for a deadly childhood disease, the diphtheria serum stands as a milestone in pharmaceutical history. Diphtheria Serum as a Technological Object: A Philosophical Analysis of Serotherapy in France 1894-1900 considers the production and use of this serum in France, analyzing the drug in terms of a technological object. To do this, Jonathan Simon draws on the philosophy of technology, exploring the application of this approach to medical drugs and suggesting how such an analysis can in turn contribute to this domain of philosophy. Starting with the manufacture of the serum from horses’ blood, Simon then considers the processes involved in transforming the blood serum into a legal medical drug and establishing its efficacy as a treatment against diphtheria. The book looks at the place the drug assumed in French society at the time, as well as the legal and political implications of its manufacture and use. All these elements are deployed to characterize a specifically French serum, as the author argues that the constitution of the drug in its full sense is not only technical but also social, political, and legal. Considering the serum as technological object facilitates a philosophical reflection on the nature of medical drugs in general by means of a thorough analysis of this particular historical example. The insights offered in this book will be of interest to students and scholars working on the philosophy of technology, particularly the medical sciences, as well as to historians of medicine, particularly those interested in the history of pharmacy.