Conceptual engineering is the method of critically assessing, improving, and replacing the concepts we use in thought and talk. Based on lectures by leading philosophers at the Conceptual Engineering Online Seminar 2020?2022, this first of three volumes is dedicated to core foundational issues in conceptual engineering: questions about the nature and varieties of conceptual engineering, whether engineering a concept necessarily preserves core features of a concept, and where the normative limits of conceptual engineering lie. It is of interest to professional philosophers with expertise in metaphilosophy or those who seek to apply the methods of conceptual engineering to issues in their own areas of specialization, as well as philosophy students who want to get acquainted with the exciting and dynamic methodological developments of their discipline. This volume includes chapters by Derek Ball & Bryan Pickel, Delia Belleri, Paul Egré & Cathal O?Madagain, Peter Gardener, Hans-Johan Glock, James Hampton, Allison Koslow, Esa Díaz León, and Sarah Sawyer.