This evaluation report examines the impact of participation in Balint Groups on the leadership development and wellbeing of Irish second-level school principals. The study is situated in a context of increasing workload and ‘worry-load’ for principals, intensified policy demands, and well-documented risks of stress, burnout, and isolation in school leadership. In response to these conditions, the Joint Managerial Body (JMB) introduced a pilot Balint Group for principals in 2015 using a co-leadership model (a principal co-leader and a group analytic psychotherapist). The initiative has since expanded to thirteen JMB-associated groups nationally, with almost 30% of voluntary secondary school principals having participated. While Balint Groups have a long history in medicine and other helping professions, their use as a leadership development intervention for school principals in Ireland is new; accordingly, the evidence base on impact in this educational context has been limited. The research adopted a qualitative exploratory design informed by case study principles. It was interpretivist in orientation and drew on psychoanalytic and leadership-development theory to frame enquiry. Data were generated through semi-structured focus groups designed to mirror the Balint co-led experience. The impact study paints Balint as both leadership development and a wellbeing intervention: it strengthens reflective capacity, perspective-taking, and the ability to hold emotional complexity – and it reduces isolation by offering a trusted peer community. The findings discussed in the report.