Abstract Counteracting perceptions of teaching as a profession with a flat career trajectory may require professional leadership opportunities for experienced teachers that differ substantively from those typically available. This evaluation study investigated the results of a professional development initiative for subject specialist teachers seconded to a leadership role in their curriculum areas. Interview and survey data supported teacher growth in subject expertise and leadership capacity attributed to the opportunities provided by the new teacher-leadership role. The findings of this study indicate expanded leadership roles may further develop experienced professionals while simultaneously supporting teacher knowledge during a period of embedding educational reform.