Arda Denkel develops a unified ontology of objecthood, essences and causation. A principal tenet is that while the basic units of the physical world are substances, particular properties are the analytic ultimates of existence. Although properties must inhere in objects, individual things are nothing more than compresences of properties at particular positions. There exist no mysterious substrata. Principles explaining how properties are held together in compresences are basically the same as those that account for essences and for causal relations. There exist no objective universals. Denkel defends a thoroughgoing particularism and offers purely qualitative accounts of individuation, identity, essences and matter. Throughout, the main alternative positions are surveyed, and the relevant historical background is traced. Since it is free of unnecessary technicalities, this book will be of interest both to specialists and to students of different levels. It can serve as a textbook in ontology courses.