The history of United States relations with the nations of Europe has centered traditionally on the pressures of events, the unfolding of social, economic and ideological trends, and the decisions of prominent statesmen. This dissertation, by contrast, tells the story of the transatlantic relationship through the lives, careers and recollections of the middle ranking American government officials who were charged with promoting and sustaining it during the twentieth century. The networks of institutions, friendships and professional associations they built were critical components of transatlantic cohesion and continuity. Moreover, their official home--the State Department's Bureau of European Affairs--emerged as one of the most powerful and influential foreign policy centers in the United States government, setting the course of American diplomacy, and fostering institutional loyalty, across four generations. In short, these people established the political prerequisites for the success of both Atlanticism and the Atlantic Community. Knowing them and their modus operandi reveals a more continuous diplomatic legacy than the record of high politics would otherwise suggest.