School self-evaluation (SSE) has emerged as a widely used approach to school evaluation in recent decades. This has occurred in the context of what is referred to as “New Public Management,” an element of which seeks to empower public institutions to make decisions locally about improving their processes and standards. Inspection regimes in many countries have developed legislative, methodological, and support mechanisms for schools to carry out SSE. This paper, by using the evolution of the SSE process in Irish education, analyses the efficacy of SSE by exploring teachers and school principals’ perceptions of both the challenges and supports concerning the integration of SSE in their schools. Results derived from this study suggest that respondents were, overall, fully aware of the support services available to them. However, support capacity challenges also emerged, in particular as it relates to data use and target setting. Importantly, it is argued that since there are striking resemblances between SSE as it has developed in Ireland and other systems, the challenges and solutions identified in this paper will have wide application in other contexts.