The 1890s saw an explosion of ambitious projects to build a massive classification of knowledge that would serve as a basis for universal catalogues of scientific publishing. The largest of these were the rival International Catalogue of Scientific Literature (London) and Répertoire Bibliographique Universel (Brussels). This essay argues that one widely influential but overlooked source of the enthusiasm for classification as a technology of search and retrieval during this period was the emergence of new methods and technologies for classifying and keeping track of people, and in particular, the criminal identification laboratory of Alphonse Bertillon located in Paris.John Shaw Billings, the doctor, medical bibliographer, and founding director of the New York Public Library, traveled to London in July 1896 to head the American delegation at the first of a series of London conferences to build an International Catalogue of Scientific Literature. In his toast at the opening banquet, he speculated that if the gathered delegates were completely successful in building the hoped-for Catalogue, "they might anticipate a time when men and things and thoughts also would be cataloged":They might look forward down the vista of years to the time when a stranger in Hyde Park would see a passer-by with such a number as 26.053, and would then at once appreciate his status in every respect, and when the novelist would proudly show that his heroine had 26 points in her character, while a rival writer had only achieved 19. (International Catalogue Conference, 1896, p. 250) Though Billings's classificatory fantasy of a world in which all individuals-whether real or fictional-had their place in a massive database was certainly tongue-in-cheek, it raises important historical questions. What