To reform instruction by moving towards student-centered approaches, research has shown that faculty benefit from support and collaboration (Henderson, Beach, & Finkelstein, 2011; Speer & Wagner, 2009). In this study, we examined the ways in which a mathematician's instruction unfolded during his participation in a faculty collaboration geared towards reforming instruction and aligning it with inquiry oriented instruction (IOI) (Kuster, Johnson, Andrews-Larson, & Keene, 2017). Results indicate the participant's mathematics background and research interests influenced how he used student thinking in his instruction. Further, there existed a tension between IOI and anticipating student thinking. Lastly, results highlight the importance of active participation in faculty collaboration to support instructional change. [For the complete proceedings, see ED606531.]