After a flourish in the 1990s and early 2000s, research into Deputy Principal leadership (also known as Assistant Principals, Assistant Heads, Deputy Heads and Middle Leaders) has since been scant. With a few notable exceptions (Snitch, 2016 & Wattam, 2017) studies focussing on Deputy Principals in Secondary Schools has not been evident in the literature. Moreover, research on the emergence of portfolio leadership by deputy Principals is even more difficult to locate. The current study examines Deputy Principals with a particular portfolio, namely Deputy Principals for Teaching and Learning (DPTL - and variants of this) in the Australian Catholic context. This senior leadership role has emerged from previous roles such as the curriculum coordinator (also Curriculum Manager, Director of Studies, Director of Teaching and Learning) and is most often at the forefront of school improvement. Key questions centre on expectations and experiences of DPTLs, challenges they experience and their beliefs about the unrealised potential of such a leadership role. Situated within an interpretive framework, the data collected for the study will be gleaned from multiple semi-structured, in-depth interviews with 12 DPTLs in Catholic Secondary Schools within the Archdiocese of Melbourne, Victoria. The study has importance for understanding how DPTLs may be developed and supported to fully impact on teacher and student learning.