Abstract: In the past two decades, the United States has applied a growing number of foreign and security measures directly targeting individuals—natural or legal persons. These individualized measures have been designed and carried out by administrative agencies. Widespread application of individual economic sanctions, security watchlists and no-fly lists, detentions, targeted killings, and action against hackers responsible for cyberattacks have all become significant currencies of U.S. foreign and security policy. Although the application of each of these measures in discrete contexts has been studied, they have yet to attract an integrated analysis. This Article examines this phenomenon with two main aims. First, it documents what I call “administrative national security”: the growing individualization of U.S. foreign and security policy, the administrative mechanisms that have facilitated it, and the judicial response to these mechanisms. Administrative national security encompasses several types of individualized measures that agencies now apply on a routine, indefinite basis through the exercise of considerable discretion within a broad framework established by Congress or the President. It is therefore best understood as an emerging practice of administrative adjudication in the foreign and security space. Second, this Article considers how administrative national security integrates with the presidency and the courts. Accounting for administrative national security illuminates the President’s constitutional role as chief executive and commander-in-chief and his control of key aspects of administrative foreign and security action. It also challenges deeply rooted doctrines underlying foreign relations and national security law, including the portrayal of the President as the “sole organ” in international relations. Administrative national security further informs our understanding of the role of courts in this context. It renders more foreign and security action reviewable in principle under the Administrative Procedure Act (APA) and provides a justification for the exercise of robust judicial power in this category.