One of the distinctive features of the idea of an Anglosphere has been a particular view of world order, based on liberal principles of free movement of goods, capital and people, representative government, and the rule of law, which requires a powerful state or coalition of states to uphold and enforce them. This chapter charts the roots as well as the limits of this conception in the period of British ascendancy in the nineteenth century, and how significant elements of the political class in both Britain and the United States in the twentieth century came to see the desirability of cooperation between the English-speaking nations to preserve that order against challengers. This cooperation was most clearly realised in the Second World War. The post-war construction of a new liberal world order was achieved under the leadership of the United States, with Britain playing a largely supportive but secondary role. Cooperation between Britain and the US flourished during the Cold War, particularly in the military and intelligence fields, and this became the institutional core of the ‘special relationship’. The period since the end of the Cold War has seen new challenges emerge both externally and internally to the Anglo-American worldview.