Abstract: At the K-12 level, there is evidence that instruction that leverages student thinking can lead to increased conceptual understanding and success for students. The ways in which instructors leverage student thinking in undergraduate STEM contexts, and what enables them to do so effectively, remains largely unexplored. We investigated how undergraduate STEM faculty use student thinking in their teaching, focusing on faculty who engage students in active learning during class. From analyzing interviews and video of a class lesson for eight undergraduate STEM instructors, we identified a group of instructors who exhibited high levels of leveraging student thinking (high-leveragers) and a group of instructors who exhibited low levels of leveraging student thinking (low-leveragers). In this talk, I will discuss key similarities and differences between these two groups of instructors and possible explanations for why some STEM instructors are leveraging student thinking and others are not.