This article examines how balance of power considerations shaped Theodore Roosevelt's role as a mediator in the 1904-5 war between Russia and Japan. Attention is devoted to his use of personal diplomacy as well as to the political and foreign policy rationales behind his overtures to Japanese and Russian leaders. To what extent did Roosevelt justify his actions as consistent with American interests and American values? If American national interests were not immediately threatened in East Asia, then what kind of concerns prompted him to intervene in the affairs of other states? Was the quest for equilibrium simply an expedient tactic by which to further the offensive power, both military and political, of the United States? Moral principles in politics and diplomacy, Roosevelt claimed, help make clear the inescapable tension between ideals and reality. The moral problem persists, he thought, because diplomacy involves choices often obscured by faulty perception, controlled by national interests, and complicated by multiple purposes and goals. I provide a brief overview of Roosevelt as strategic thinker and then moves on to take up his personal style of diplomacy.