ABSTRACT Classroom-based teacher leaders assume a variety of roles including being a model of effective instruction and supporting others to improve instruction. However, some teachers may be reluctant to engage in novel pedagogies. In working with 34 experienced teachers in their final year of a teacher leadership fellowship, we developed a rehearsal activity toward the co-creation of principles for supporting reticent colleagues. Using thematic content analysis, we analyzed rehearsal scripts and subsequent discussion. We examined what their rehearsals revealed about their perspectives on supporting reticent colleagues and how rehearsals can be used to build knowledge for leadership practice. We found evidence that considering realistic scenarios through scripting and rich discussion was a useful approach for supporting emerging leaders. Teacher leaders drew on their expertise to collectively develop three guiding principles for supporting reticent colleagues. We re-envisioned rehearsals to leverage the knowledge of experienced teachers and identified four components of effective rehearsal for building networked expertise.