This thesis examines the ramifications of Britain’s negotiations to join the European Community (EC) on Anglo-American relations, 1969-1974. It adds to the historical debate by showing that strong Anglo-American political, economic, and defence relations continued under Heath and Nixon. The prevailing view in this area is that the British Prime Minister Heath sought to re-orientate foreign policy away from the ‘special’ Anglo-American relationship towards the EC. Moreover, it is believed that the Nixon presidency developed a sceptical view of an enlarged, competitive EC. Thus, the Heath-Nixon period is viewed as a low point in the post-1945 alliance because of the EC enlargement. However, while gaining entry into the EC was the top priority for the UK government, Heath and Whitehall sought to preserve close Anglo-American cooperation. Moreover, Nixon considered Western European integration and Anglo-American relations to be important components of the Atlantic Alliance and his Cold War strategy. Tensions did grow: over the substance of China and Middle Eastern policy, the unilateral dismantling of the Bretton Woods system, and the ‘Year of Europe’. But these episodes also showed the strength of the Anglo-American partnership. In the economic sphere the EC enlargement negotiations planted the UK into the middle of US-EC trade conflict over unfair trading practices. Furthermore, the UK’s entry into the EC altered the status of sterling, resulting in a delicate change to Anglo-American economic relations. Yet close cooperation continued in trade and monetary affairs, independent from the enlarged EC. In the field of defence policy, Anglo-American ‘special’ relations actually strengthened under Heath and Nixon with the Polaris missile system upgrade and the continuation of sharing military facilities and intelligence. The 1970s witnessed a subtle policy-making process and adjustment in diplomatic relations, less coherent and straightforward than previously presented. Using recently released government documents, this thesis contributes to developing our understanding of 1970s Anglo-American relations and European integration.