This chapter reviews the literature on issue ownership and competence, and offers a response. It navigates the theories and evidence from which the authors construct their argument for the three concepts of issue competence used in the book; ownership, performance and generalised competence. The chapter highlights confusion in understandings of issue ownership as a long-term reputation and a short-term lease; considers measurement problems in the analysis of issue ownership (especially relating to partisan endogeneity); and explains the different implications of long-term and short-term competence. It explains why issue ownership should be separated from performance, why the concept of valence has come to mean almost everything and nothing in the formal literature, and why the term ‘valence’ should be used with caution. The authors highlight a general notion of competence, how that builds on existing research and why and how it arises. The chapter outlines how the different concepts of public opinion can be measured for the purpose of analysis, at both an individual and aggregate level, and how they are defined and measured throughout the book.