This is a ground-breaking history of school and college inspection in Wales. With contributions from two former chief inspectors, two former HMI and leading historians, it offers an authoritative account of how the inspectorate has changed over time. Since their beginnings in 1839, HMI have steered a course between being instruments of the state and independent influencers of education policy and practice. They have been much-valued catalysts for improvement in schools and colleges, and have had a key role in promoting the teaching of the Welsh language, history and culture. This book is written for anyone concerned with the history of education in Wales, the history of accountability in education, with approaches to school improvement, and the extent to which HMI have influenced or been at odds with education policy making. At a time when the inspectorate itself is under review, this is a timely reminder of its wide-ranging services.