The first-ever Quadrennial Homeland Security Review (QHSR) comes amid much expectation and interest. Homeland security encompasses the most sweeping reform in government in nearly half a century, and makes explicit the realization that the evolving international security landscape bears directly on our domestic security. But we have also learned that security is not an end in itself; rather, it is an important means to a vital end: preserving the values, principles, and way of life we pursue as Americans. A review of homeland security could take many forms—from a retrospective and assessment of the past, to an analysis of current programs and activities, to a view of what the future might bring. Nonetheless, Congress made clear in its direction to the Department of Homeland Security (DHS), the principal author of this report, that the QHSR should delineate a homeland security strategy, including an outline of priority mission areas, not simply for DHS, but for the homeland security enterprise as a whole—embracing Federal, State, local, tribal, and territorial governments, nongovernmental organizations, the private sector, as well as individuals, families and communities. Such a strategic analysis would then serve as a basis for a deeper review of the many programs and budgets required to execute the full range of homeland security missions. Congress also sought to better understand the resource and organizational implications of an evolving strategic view of homeland security. What was clear from the start, however, is that any articulation of strategy or analysis of specific programmatic or resource tradeoffs—either within DHS or across the broader homeland security enterprise—had to be firmly rooted within a comprehensive strategic understanding of homeland security. For example, “What is homeland security?” “How is the homeland best made secure?” “What does it mean to be prepared?” Eight years after 9/11, these questions still echo widely among the many homeland security stakeholders. The QHSR marks the beginning of a multi-step process to answer these questions. It offers a vision for a secure homeland, specifies key mission priorities, outlines goals for each of those mission areas, and lays the necessary groundwork for subsequent analysis and recommendations. As an immediate follow-on and complement to the QHSR, an important “bottom-up” review of DHS was begun in November 2009 that will look to align the Department's programmatic activities and organizational structure with the mission sets and goals identified in the QHSR.While the primary purpose for the QHSR is to outline the strategic framework to guide the activities of participants in homeland security toward a common end, it is equally important to note what the QHSR is not. The report is not a resource prioritization document, although in identifying key mission areas for priority focus, it is highly indicative of where those priorities should lie. Nor does the QHSR detail the roles and responsibilities of Federal or other institutions for each mission area. Instead, the QHSR functions as a strategic document that seeks to answer the most fundamental questions that many Americans still ask about homeland security. By describing a forward-looking homeland security vision for the Nation and the requisite set of key mission areas, goals, objectives, and outcomes, integrated across the breadth of the homeland security landscape, it also will serve as a roadmap to keep America safe, secure, and resilient in the years ahead.