This study examines the role of school inspections in driving improvement within an initially low-performing secondary school in Ireland over a 15-year period. Through a longitudinal case study, the research investigates the impact of three inspection cycles on school development. The study draws on a thematic review of literature to contextualise the evolving functions, roles, and frameworks of the Irish Inspectorate from 1996 to the present, a period marked by significant changes in inspection practices. Nineteen semi-structured interviews with stakeholders provide qualitative insights, which are analysed alongside the literature to understand the dynamics at play in the school's improvement journey. Findings suggest that despite Ireland's low-stakes inspection system, strong trust in the expertise of inspectors, the respected position of the inspectorate, and alignment between the inspection findings and the school's internal self-evaluation were instrumental in fostering acceptance of the initial critical report. This acceptance by school leadership, extended gradually to the entire school, underscores inspection as a potent catalyst for sustainable school improvement. The study concludes that, under specific conditions, school inspection can indeed serve as a highly effective mechanism for long-term educational improvement.