During his forty-year career, E. J. Lowe established himself as one of the world’s leading philosophers, publishing eleven single-authored books, four co-edited collections, and well over 200 articles in journals and edited volumes. His scholarship was strikingly broad, ranging from early modern philosophy to the interpretation of quantum mechanics. His most important and sustained contributions were to philosophy of mind, philosophical logic, and, above all, metaphysics. E. J. Lowe was committed to a systematic, realist, and scientifically informed neo-Aristotelean approach to philosophy. This volume brings together essays by philosophers who share these concerns, addressing interrelated themes of his work. In particular, these essays focus on three closely connected topics central not only to Lowe’s work, but also to contemporary metaphysics and philosophy of mind in general: ontology and categories of being; essence and modality; and the metaphysics of mental causation.