Dag Hammarskjold was one of the most important men of his generation. This study will deal with his valuable contribution to the development of the United Nations and, specifically, the Office of Secretary- General. In a discourse of this kind it is impossible to assess Mr . Hammarskjold ' s full contribution to the field of international administration. Briefly stated, I have tried to analyze the conditions which encouraged or impelled him to expand the Office and the philosophy and methods by which he did so . I have concentrated on the developments for which he was directly and personally responsible. The author has drawn inspiration from , and based his study on, a wide range of sources. United Nations documents, books, journals , and newspapers have served as the bulk of research materials for this endeavor. However, no bibliography could encompass the full spectrum of sources that he has found useful . Though their results may show less tangibly , conversations never fail to add new insight and exhaust the possibility of valid criticism. The author is particularly grateful to Mr. Carl Major Wright of the United Nations , Mr. N. K. G. Tholand, Mr . Hubert de Besche, Swedish Ambassador to the United States, and Mr. Jean-Jacques de Dardel , Swedish Minister to the United States, for abiding his preoccupation with this assay. The author would also like to express his appreciation to the faculties of the Woodrow Wilson Department of Government and Foreign Affairs of the University of Virginia and the Department of Political Science of the University of California who have supervised and encouraged his study of foreign relations. Grateful acknowledgement should also be made to the staff of Alderman Library of the former institution for their valuable assistance in helping him locate many of these research materials. Finally, the author is particularly indebted to Professors Alfred Fernbach, Herbert Emmerich, and Laurin Henry, whose counsel has guided him through this study.