Introduction. Individual Substance in the Discourse Metaphysics: Some Problems. Part I. The Genesis of a Complete Being. Section 1. Individuals and Concepts at the Origins of Leibniz's Project. Section 2. Origo Rerum ex Formis: The (Onto-)logical Construction of a World from Conceptual Atomism to Individual Substance. Section 3. Series Rerum. The Causal-Temporal Structure of Things: Model Metaphysics and Philosophy of Mind. Interlude: On Truth. Part II. A Logico-Ontological Framework for Substances. Section 4. Categories (1). Concepts, Things and the Reform of the Category Table. Section 5. Complete Concept and Substance: The New Alliance of Concept and Thing. Section 6. Categories (2). The Theory of Conditions in the Categorial Framework. Part III. Notio Completa: Complete Concept and Individual History. Section 7. The Debate on DM 13: Some Leading Ideas. Section 8. Scientia Dei: Individual Concepts in God's Mind. Section 9. Law, Concept and World: The Nomological and Relational Structure of Complete Concepts. Post-Script 1. Individual Concepts and the Infinitary Solution. Post-Script 2. Individual Concepts and Leibniz's Metaphysics of History. Substances, Concepts and Individual Essences: Some Concluding Remarks.