Using previously undocumented archival material, this dissertation examines missionaries from the Brethren agency Echoes of Service. A consideration of missionary primitivism provides a more complex picture of the mission engagement with China. The Brethren are a radical evangelical group that originated in Britain in the nineteenth century. They looked backwards to an original ideal of Christian faith and church organisation, which they sought to revive in the modern world. This was a reaction against modernity, but it should also be seen as part of modernity. The Brethren attempt to take missionary primitivism to China demonstrates how Christianity in the West and in China during this period were mutually constitutive, with influences circulating freely and unpredictably between the two.The thesis is organised into five chapters which develop these themes. Chapter one focuses on changes taking place in Britain at the start of the twentieth century, and shows how the promotion of missionary primitivism abroad was seen as essential for the health of the Brethren movement at home. In particular, missionary supporters elevated the individual missionary who operated according to simple, scriptural principles. Accordingly, the remainder of the thesis focuses on a number of individuals who sought to enact this model in different ways and in a variety of settings. Chapter two examines Watchman Nee, the founder of the Little Flock movement. Nee appropriated missionary primitivism as a means of establishing a truly independent Chinese Christianity, and his success provoked extreme and contrasting responses from Christians in the West. In addition, although Nee emphasised the primitive character of his movement, its immediate context was the cosmopolitan, bourgeois world of China's treaty-ports. Chapters three and four examine the work of Brethren missionaries on China's margins, specifically on the Sino-Mongolian and Sino-Tibetan borders. Missionary primitivism lauded its pioneers in these 'regions beyond', which were seen as arenas where a Brethren missionary could truly fulfil their calling. The remoteness of these places also meant that the modernity of a missionary became more pronounced. Through administering modern medicine or as a result of business or political contacts, missionaries would often become important figures in the mediation of modernity in these regions.Finally, chapter five examines missionary primitivism in the context of decolonisation. Two points of continuity are particularly noted: first, the survival and growth of the Little Flock in communist China has led to it becoming a significant feature of the landscape of popular religion in contemporary China. The memorialisation of Watchman Nee has also left an enduring legacy among Christians in the West. Second, the Echoes missionary George Patterson, after being involved in the mission to Tibet, began reporting about and campaigning for the Tibetan cause. Though he saw this as a continuation of his missionary calling, it has led to him promoting causes at tension with his earlier convictions. These regional stories of missionary primitivism serve to challenge existing paradigms of modern Chinese history. They demonstrate that, rather than seeing the modern as superseding the primitive, the relationship between the two should be seen as a coterminous and symbiotic one. In addition, the emergence of modern and primitive forms should be seen as a product of the free movement of influences between China and the West, and of their mixing in a variety of contexts.