While military history abounds in the dramatic fare of battles and campaigns, definitive analysis of the evolution of the organization and administration of the departmental headquarters in the capitals has been a relatively neglected field. Yet upon the efficiency and effectiveness of the administrative apparatus needed to build, train, equip, and supply armed forces depends much of the success in the test of battle. The present study grew out of a monograph originally designed to provide a simple guide to the principal changes in Army departmental organization since 1942. Expanded later to cover the period beginning with 1900, the era of reform introduced by Secretary of War Elihu Root, and to provide a larger measure of analysis, this study traces changes relating to Army management in the central headquarters down to the early 1960s when new and dramatic reforms in Army organization were carried out during the regime of Secretary of Defense Robert S. McNamara. The account focuses on a single but important theme -the management of the Army administrative and logistical structure in the era of America’s rise to global power. It fills a gap in the literature and is presented as a contribution to the field of organizational and administrative history. While the author’s focus is on the Army headquarters staff, he indicates parallel trends in organization in industry and government and relates his theme to historic conflicts over centralization of control. The volume presents a useful survey in a field of continuing importance that should be of interest to administrators and managers both in and out of the Army as well as to students of military history and public administration.