Mathematical identities have largely been cast in this book in terms of the relationships people form with mathematics and, importantly, with other actors and processes in the environs of mathematics. Given the educational focus, a main (but not sole) concern is with the mathematical identities of students, but also with teachers and trainee teachers as the main mediators of student learning who bring their own mathematical identities with them to their classrooms. There are concerns with the remnants of earlier (and ongoing) mathematical experiences on adults, including those who have, for a variety of reasons, come back to mathematics, and how these experiences shape their present-day processes of becoming. Varying conceptions of identity have been used to explore these relationships, falling into three broad groupings: sociocultural, discursive, and psychoanalytic. In this response, I draw across the chapters and approaches, but primarily on a sociocultural perspective to question whether mathematical identities matter.