The purpose of this paper is to explore alternative concepts for structuring mission capability packages (MCPs) around which future U. S. military forces might be configured. From the very outset of this study group's deliberations, we agreed that the most useful contribution we could make would be to attempt to reach beyond what we saw as the current and commendable efforts, largely but not entirely within the Department of Defense, to define concepts for strategy, doctrine, operations, and force structure to deal with a highly uncertain future. In approaching this endeavor, we fully recognized the inherent and actual limits and difficulties in attempting to reach beyond what may prove to be the full extent of our grasp. It is, of course, clear that U.S. military forces are currently the most capable in the world and are likely to remain so for a long time to come. Why then, many will ask, should we examine and even propose major excursions and changes if the country occupies this position of military superiority? For reasons noted in this study, we believe that excursions are important if only to confirm the validity of current defense approaches. There are several overarching realities that have led us to this conclusion. First, while everyone recognizes that the Cold War has ended, there is not a consensus about what this means for more precisely defining the nature of our future security needs. Despite this absence of both clairvoyance and a galvanizing external danger, the United States is actively examining new strategic options and choices. The variety of conceptual efforts underway in the Pentagon to deal with this uncertainty exemplifies this reality.