From the air raid warning and plane spotting activities of the Office of Civil Defense in the 1940s, to the Duck and Cover film strips and backyard shelters of the 1950s, to today's all-hazards preparedness programs led by the Department of Homeland Security, Federal strategies to enhance the nation's preparedness for disaster and attack have evolved over the course of the 20th century and into the 21st. Presidential administrations can have a powerful impact on both national and citizen preparedness. By recommending funding levels, creating new policies, and implementing new programs; successive administrations have adapted preparedness efforts to align with changing domestic priorities and foreign policy goals. They have also instituted administrative reorganizations that reflected their preference for consolidated or dispersed civil defense and homeland security responsibilities within the Federal government. Programs were seldom able to get ahead of world events, and were ultimately challenged in their ability to answer the public's need for protection from threats due to bureaucratic turbulence created by frequent reorganization, shifting funding priorities, and varying levels of support by senior policymakers. This in turn has had an effect on the public's perception of national preparedness. Public awareness and support have waxed and waned over the years, as the government's emphasis on national preparedness has shifted. An analysis of the history of civil defense and homeland security programs in the United States clearly indicates that to be considered successful, national preparedness programs must be long in their reach yet cost effective. They must also be appropriately tailored to the Nation's diverse communities, be carefully planned, capable of quickly providing pertinent information to the populace about imminent threats, and able to convey risk without creating unnecessary alarm. The following narrative identifies some of the key trends, drivers of change, and lessons learned in the history of U.S. national preparedness programs. A review of the history of these programs will assist the Federal government in its efforts to develop and implement effective homeland security policy and better understand previous national preparedness initiatives.