The impact of public law depends on how politicians secure control of public organizations, and how these organizations in turn are used to define national security. Governing Securityexplores this dynamic by investigating the surprising history of two major federal agencies that touch the lives of Americans every day: the Roosevelt-era Federal Security Agency (which became today's Department of Health and Human Services) and the more recently created Department of Homeland Security. Through the stories of both organizations, Cuellar offers a compelling account of crucial developments affecting the basic architecture of our nation. He shows how Americans end up choosing security goals not through an elaborate technical process, but in lively and overlapping settings involving conflict over agency autonomy, presidential power, and priorities for domestic and international risk regulation. Ultimately, as Cuellar shows, the ongoing fights about the scope of national security reshape the very structure of government, particularly duringor in anticipation ofa national crisis.