Professor William Kay, one of the world’s leading Pentecostal theologians, discusses the origins of Pentecostalism at the end of the nineteenth century with Dr Frances Knight. He describes how they came to have a distinctive identity partly by being ‘pushed out’ of existing Christian groups, partly because of their distinctive practices such as Speaking in Tongues and practising adult baptism, and partly as a result of their pacifist reactions to the First World War.