It is widely known in Wales that some nineteenth-century schoolchildren were victims of the Welsh Not. It was a wooden board, hung around the neck of children heard speaking Welsh, and was often accompanied by corporal punishment. The Welsh Not is then associated with the decline of the Welsh language. Yet, despite its iconic status, there has been no previous study of where, when and why the Welsh Not was used. This book is an account of the different ways children were punished for speaking Welsh in nineteenth-century elementary schools and the consequences that this had for children, communities and the linguistic future of Wales. It demonstrates how the exclusion of Welsh actually hindered pupils in learning English – the very thing it was designed to achieve. Thus, gradually over the century, Welsh came to be increasingly used in schools as part of a more effective mechanism in the Anglicisation of Wales.