An Epistemology of the Concrete brings together case studies and theoretical reflections on the history and epistemology of the life sciences by Hans-Jörg Rheinberger, one of the world’s foremost philosophers of science. In these essays, he examines the history of experiments, concepts, model organisms, instruments, and the gamut of epistemological, institutional, political, and social factors that determine the actual course of the development of knowledge. Building on ideas from his influential book Toward a History of Epistemic Things, Rheinberger first considers ways of historicizing scientific knowledge, and then explores different configurations of genetic experimentation in the first half of the twentieth century and the interaction between apparatuses, experiments, and concept formation in molecular biology in the second half of the twentieth century. He delves into fundamental epistemological issues bearing on the relationship between instruments and objects of knowledge, laboratory preparations as a special class of epistemic objects, and the note-taking and write-up techniques used in research labs. He takes up topics ranging from the French “historical epistemologists” Gaston Bachelard and Georges Canguilhem to the liquid scintillation counter, a radioactivity measuring device that became a crucial tool for molecular biology and biomedicine in the 1960s and 1970s. Throughout An Epistemology of the Concrete, Rheinberger shows how assemblages—historical conjunctures—set the conditions for the emergence of epistemic novelty, and he conveys the fascination of scientific things: those organisms, spaces, apparatuses, and techniques that are transformed by research and that transform research in turn.