When theory should guide action, what kind of theorizing do we need?

Theory in mathematics education can play different roles, among them the role of guiding the action of different stakeholders (e.g., teachers, teacher educators, curriculum designers, researchers, and policymakers). Researchers and practitioners alike have argued that the theories typically provided by researchers are often not sufficient for guiding action and have called for research-practice partnerships as, in part, a means of generating theory to guide action. So far, we have only partially recognized which theories can guide action, and how researchers and practitioners can engage in research-practice partnerships in order to generate theories which can better guide practitioners’ actions. In this chapter, we disentangle different kinds of theory elements and their interplay, in service of guiding practice, and we discuss typical challenges in reaching the goal. We draw from existing literature and our own experiences to suggest how discourses of researchers and practitioners can be transformed so that theories are better positioned to guide practitioners’ actions. We suggest acts of joint theorizing and supportive conditions which can increase the chance that a developed theory can guide stakeholders’ actions. Finally, we reflect on the implications for the culture and policies within the academic field of mathematics education.