John Picarelli, NIJ program manager, introduces the panel presentation by noting that at the time of this seminar, NIJ had 23 open studies that were examining issues related to preventing and intervening in violent extremism in U.S. communities. He indicated that these studies are in two categories: 1) those that focused on gaining a better understanding of why radicalization occurs and what can be done to detect it in the United States; and 2) based on this information, what can be done to prevent and intervene in violent extremism. The panel involved presentations and discussions of studies related to the latter category. Panelist John Horgan, professor of global studies and psychology at Georgia State University, summarized his research on children's involvement in the Islamic-state movement, self-concealment among terrorist organizations, attack behaviors associated with lone-acting terrorists and less ideological mass murderers, and the evaluation and effectiveness of programs intended to counter violent extremism. Panelist David Schanzer, director of the Triangle Center on Terrorism and Homeland Security at Duke University, focused on the challenge and promise of using community policing strategies to prevent violent extremism. Panelist Michael Downing, commanding officer of the Counterterrorism Special Operations Bureau of the Los Angeles Police Department, addressed how democratic civilian policing models can be tailored to counter violent extremism in their communities.