The members of the reserve components of the United States constitute a strategic means, to enable the execution of U.S. strategy. This has been clearly demonstrated in the recent Global War on Terrorism (GWOT). Unfortunately, in the struggle for limited resources within the U.S. democracy, and in terms of recent events, the U.S. Army and its reserve components now appear to have been under resourced in terms of personnel for over a decade. While the members of the reserve components have made tremendous contributions to the GWOT that vastly outweigh the relative cost of maintaining them, they are nearly exhausted under current mobilization policy. Among those most critical and difficult to replace today are the experienced mid-grade officers of the Army's reserve components. The Army uses a model called Mobilization Manpower Planning System, or MOBMAN, to project personnel requirements, casualty figures, and indirectly as a means of setting goals for inventory of reserve personnel. MOBMAN only supported full mobilization planning until it was modified to include partial mobilization planning in 1994. Today, the U.S. is engaged in a protracted campaign at partial mobilization. Recent planning did not give adequate consideration to the possibility of a large scale, extended partial mobilization event with its 24 month service limit. The Cold War models estimated requirements to replace projected casualties in percentages of the force. Current mobilization policy requires nearly every mobilized reservist to be replaced at, or before, the 24 month mark, as though they were a casualty. This has caused the U.S. to rapidly exhaust forces reduced in size during the 1990s. This paper examines issues which brought us to where we are today, how much downward trend we can continue to expect, and some options for maintaining or improving critical reserve personnel inventories.