While architects who adhered to tradition could claim the support of Church documents and the clergy, modernism was advocated and practised by many Roman Catholic church architects and increasingly welcomed by the clergy after 1955. This chapter examines some of the reasons behind this turn towards modernism, while the following chapters explore in more detail the variety of ways in which modern architects approached church design. Modernism could bring to the Church the promise of an institution that was part of the modern world and relevant to the needs of its inhabitants, a dierent vision of the institution to that proposed by architects such as Velarde or Goodhart-Rendel. This was a world characterised by rapid change, by the vast movements of people rehoused in new towns and estates, by new and exciting products and materials and, above all, by a feeling of optimism for the future as war and its aftermath of economic struggle became a memory. The Catholic Church was not hermetically sealed from this general cultural climate; on the contrary, its members were inhabitants of the modern world, wished to understand the Church in its terms and hoped to present a public face of the Church that would be well regarded by modern society. Modern architecture oered potential to achieve these aims.