Jonas Proast’s argument against religious toleration is often accepted as far more compelling than the ‘Mile End’ argument presented by Locke in his Third Letter for Toleration, which has largely been replaced by twentieth century versions of Social Contract Theory and theories of rightsRights based on the concept of the Westphalian System. These theories have coloured the way in which Locke’s letters on toleration are read and a significant element of their content and context has been elided. The key element missing from modern readings is Locke’s reliance on travel literature and particularly the Spanish travel literature, which formed the basis of his theory of Natural Law. Locke followed his ‘Mile End’ remark with a discussion of America largely drawn from José de Acosta whose works were part of a much older and more philosophically sophisticated debate on toleration and coercion than that in Protestant Europe, which is often seen as the dominant or even the sole tradition of toleration. A focus on the ‘Mile End’ passage in Locke’s Third Letter makes it possible to explore this wider context of Locke’s case for toleration.