In this workshop, I will engage participants in thinking about the challenges of measuring strategy flexibility on the example of mathematics, for the purposes of research. I begin by introducing, defining, and giving examples of strategy flexibility in mathematics. I then discuss the various assessments that researchers, including my research group as well as others, have developed to capture the essence of as well as the nuances of this construct. Participants will have the opportunity to critique these existing measures as well as brainstorm improvements for use in future work. Note: Advanced knowledge of mathematics is NOT necessary to fully engage in this workshop. The level of mathematics needed to think about assessments of strat-egy flexibility will be (at the most advanced) from grades 5 to 8.