Distributed Leadership (DL) is a feature of education in many jurisdictions. Similarly, in Ireland the principles of DL have been adopted as part of a quality framework to underpin a system that provides high quality student care, learning and teaching. This model necessitates an alignment of senior leaders (SLs) and middle leaders (MLs) whose actions are informed by the needs and priorities of their particular school. The traditional notion of the ML position as a management position is changing. The evolution requires a reconceptualisation, a transformation of the role and how we support and develop it to ensure that MLs are an integral part of the leadership structure of the school. This pragmatic research explored the PD needs of MLs in Irish, Education and Training Board (ETB) post-primary schools. It involved a mixed-methods, exploratory sequential study. Stage one involved a set of five semi structured interviews with AP I post holders. These were used as an instrument to develop the online surveys. Stage two involved quantitative research. Online surveys were distributed to all ETB schools in the republic of Ireland. In stage three a summary of the findings of the survey were shared with ten AP Is who were subsequently interviewed to gain further insights. The study illustrated that the development of MLs requires the support of SLs, skills development, a supportive school culture and combined training for senior and middle leaders which should be facilitated by an independent person.