China’s recent economic reforms have opened its economy to the world. This policy, however, is not new: in the late nineteenth century, the United States put forward the Open Door Policy as a counter to European exclusive ‘spheres of influence’ in China. This book, based on extensive original archival research, examines and re-evaluates China’s Open Door Policy. It considers the policy from its inception in 1899 right through to the post-1978 reforms. It relates these changes to the various shifts in China’s international relations, discusses how decades of foreign invasion, civil war and revolution followed the destruction of the policy in the 1920s, and considers how the policy, when applied in Taiwan after 1949, and by Deng Xiaoping in mainland China after 1978, was instrumental in bringing about, respectively, Taiwan’s ‘economic miracle’ and mainland China’s recent economic boom. The book argues that, although the policy was characterised as United States ‘economic imperialism’ during the Cold War, in reality it helped China retain its sovereignty and territorial integrity.