The literature on intersectionality is well-developed and shared among feminist scholars. However, its operationalization and concrete implementation by activists have less often been the object of inquiry. Whereas intersectionality is a concept loaded with normative ideas, it is less clear what it represents for activists and how they implement it. To take as an object of inquiry practices of intersectionality in feminist movements raises a question of definition and method. In many contexts activists do not know what intersectionality is or means. How should we then define what is an intersectional practice, and who should have the authority over this definition? Should we evaluate intersectional practices using the academic definition of the concept; or should we define intersectionality by looking at activists’ discourses? In this paper I use a comparative research on feminist organizations in France and Canada to reflect on these issues and on their methodological consequences.