Non-profit organizations (NPOs) in the United States have made considerablecontributions to its national security. They can be roughly divided into three categories: intellectual support organizations, advocacy organizations, and action-oriented organizations.NPOs have played a variety of roles in the domain of national security, ranging from think tanks, providers of interdisciplinary expertise in science and technology, clubs for “insiders,”educators for the public, totraining bases and revolving doors for human resources andand facilitators of the implementation of national security strategy. Several factors can explain the deep involvement of NPOs in national security affairs in the USA: its historical and cultural heritage, the rapid growth of NPOs in the past three decades, the U.S. government’s increasing attention to and support of NPOs, and the aftermath of 9/11 attacks.