The Welsh education system is engaging in a wide-ranging series of reforms and, as part of these reforms, is moving towards an accountability system that aims to work collaboratively with teachers and school leaders in a self-improving system. The aspiration is to move away from accountability structures that are built around high-stakes performative measures. Reform in this area implies change at procedural and cultural levels, and this article presents a research project that explores teacher, school leader and challenge adviser perspectives on accountability, through the lens of narrative inquiry, to identify ways in which accountability is currently constructed and understood. Findings indicate that teachers develop narratives that are focused upon anxiety over impact, whilst leaders focus on critiquing modes of measurement, and that accountability, therefore, is problematised in differing ways by different cohorts of professionals. Furthermore, the leaders' narratives explore an unresolved tension between the desire for an accountability system which is nuanced and detailed, and the desire for an accountability system which is also clear and unambiguous. It is argued that successful reform will have to engage explicitly with these different ways of understanding accountability if it is to be successfully co-constructed with the profession in the current context.