The definitive exploration of how medieval and early modern thinkers answered philosophy's most fundamental question: what makes an individual truly individual?What makes an individual this particular being rather than another? This deceptively simple question—known as the problem of individuation—stood at the heart of medieval metaphysics and shaped the trajectory of Western philosophy. Individuation in Scholasticism, edited by Jorge J. E. Gracia, offers the most comprehensive exploration available of this enduring philosophical problem. Bringing together sixteen distinguished scholars, this volume traces the evolution of theories of individuation across Latin, Islamic, and Jewish traditions, illuminating a rich intellectual dialogue that spans five centuries. From Avicenna and Averroes to Aquinas, Scotus, Ockham, and Suárez, the contributors examine how major thinkers and schools confronted questions of identity, unity, and difference. Each chapter provides rigorous analysis grounded in historical context, revealing both the diversity of scholastic approaches and their profound influence on early modern philosophy, including Leibniz. Bridging traditions, periods, and methodologies, this volume fills a critical gap in the study of metaphysics and medieval thought. It is an indispensable resource for scholars and students seeking to understand how the concept of individuality was forged, contested, and transmitted across generations.