The Peer-Led Team Learning (PLTL) model has shown to have a positive effect on undergraduate Peer Leaders’ (PL) professional and personal growth. One factor that could explain these effects is the development of metacognitive abilities. We are currently exploring this concept through an investigation of the phenomenon of transfer of knowledge as an indicator for metacognitive ability. An explanatory sequential mixed methods study with a case-selection variant design to explore metacognitive abilities in undergraduates. We have developed The Approaches to Peer Leading Inventory (APLI) by adapting the Approaches to Teaching Inventory (ATI). Preliminary data shows PLs progressed to more student-centered pedagogy over the semesters led. These data will be paired with the results from a metacognitive questionnaire which measures three subcomponents of metacognition. These surveys will be used to create cases based on metacognitive ability and workshop approach. A series of think-out-loud problem solving observation sessions and a semi-structured interviews will be conducted to further our exploration of metacognitive skill development.