The U.S. Army has seen its missions grow in number and intensity in recent years with the global war on terrorism and the invasion and occupation of Iraq. The resulting levels of stress that have been placed on the Army's active and reserve components have generated public debate about whether the Army's present organization is adequate for the roles that the service is playing now and will play in the foreseeable future. At the same time, the Army has begun an extensive restructuring effort, called modularity, that is designed to significantly alter how the service is organized and how it operates in the field. This Congressional Budget Office (CBO) study - prepared at the request of the House Committee on Armed Services - examines the Army's capability to fight wars, sustain long deployments, and deploy rapidly to overseas operations, as well as its dependence on personnel and units in the reserve component. This study also analyzes eight options for restructuring the Army, each of which would either increase the Army's ability to perform some types of missions or decrease its reliance on the reserve component. The options offer a broad overview of the general types of policy choices and trade-offs that decisionmakers will face when considering the size, structure, and capability of any plan for reorganizing the Army. In keeping with CBO's mandate to provide impartial analysis, this study makes no recommendations.