The purpose of this study is to examine organisational structures and practices in Irish primary school settings, in order to identify features which are in support of sustainable leadership. Sustainable leadership in this study is viewed as a contextual and adaptive construct, supporting leadership activities which help organisations to meet their needs in the long term. In accordance with the wider literature, the study proposes that sustainable leadership practices support school agency and improvement. The study draws heavily upon sustainable leadership theory advocated in the wider international literature and also connects with research relating to Irish primary education in an era of unprecedented economic and social change. Specific issues are framed using the three fundamental principles of sustainability proposed by Hargreaves and Fink (2006). The core principles align with the early career stages of principal leaders and are categorised as; leading learning, succession planning and distributed leadership activities. The study seeks to investigate the perspectives and experiences of Newly Appointed Principals (NAPs) in Irish primary school settings, along their career trajectory from aspiring to novice principal leaders in schools. A combination of quantitative and qualitative methodologies were utilised to investigate the key research questions devised in this case. A preliminary national survey of NAPs was administered. Perceptions and experiences relating to this population grouping were gathered using items linked to the three core principles of sustainability. These items were developed following a review of the wider literature. Informed by the survey data, in-depth interviews with NAPs were carried out. The aim was to complement and enrich the survey data. Both datasets were integrated to produce a rich body of evidence related directly to the concept of sustainable leadership. The study contributes to existing research in Ireland and expands it by documenting evidence relating to a specific leadership sub sample. It examines also, aspects of early career leadership experiences and practices which have yet to be researched in the Irish education field. The findings indicate that there are a number of significant issues which inhibit sustainable leadership practices in Irish primary school contexts. These issues are framed and linked specifically to instructional leadership capacity, succession planning procedures and structures, and distributed leadership practices in this study.