Much recent literature of educational leadership acknowledges the need for school Principals to prioritise particular leadership dynamics in school communities characterised by significant diversity (ethnic, cultural, religious or linguistic). Commitments on the Principal’s part to inclusion, equality, social justice and ethical practice are to inform such leadership. Stemming from these commitments, actions that are context-sensitive, dialogical, critically-reflective, collaborative, creative and responsive to the concerns of multicultural education are seen to make up the day-to-day business of the Principal. In this dissertation, I argue that ‘Phronesis’, as conceptualised in recent neoAristotelian philosophical articulations of Practical Wisdom and Practice, offers school Principals a way of understanding how to ‘be’ and ‘become’ such a Principal - thereby making good what is arguably a lack in the school leadership literature itself. The dissertation incorporates an action-research self-study of one year of my Practice as a school principal attempting to embody these commitments in a school community with significant diversity. Through selected extracts from a reflective journal, the study offers thick description of issues arising in and the atmosphere pervading this diverse Irish primary school. The layers of reflection, built into the Journal excerpts in the first instance and into the academically informed analysis that accompanies each excerpt in the second instance, are intended to offer insight into significant challenges and dilemmas confronting me in my leadership role as Principal in this quite specific school context. The conclusions of the study summarise the professional learning and development that accrued for me through engagement in this research/practice over the two years of the study. Tentative claims regarding the refinement of the originally articulated Practice Framework, in terms of more developed understandings of the dynamics of dialogue, action and critical-reflection, are presented and defended. Emerging personal lay theories about the location of the primary school in the broader multicultural society are proposed.