The topic of homeland security includes a broad array of missions and mission areas ranging from national missile defense to military assistance to civil authorities. The topic has recently attracted a great deal of attention due to the public's heightened awareness of the variety and nature of emerging threats and of the United States vulnerabilities to them. The Army Staff was assigned to investigate the Army's role in homeland security from a strategic, rather than a legal or procedural perspective. The author achieves this perspective by placing homeland security missions within the larger spectrum of operations. In so doing, he exposes potential problem areas--missions requiring more or different force structure than that already available--for further action by the Army. He also recommends that the Army consider alternative force-sizing metrics that include, as a minimum, the high-end homeland security identified in the study.