In establishing the Department of Homeland Security (DHS), the Administration and Congress determined that science and technology should play a key role in the nation's efforts to counter terrorism. Congress included an S&T, directorate prominently in the DHS. Within that directorate, is the Office of University Programs, which is responsible for sponsoring a number of homeland security centers of excellence in the nation's universities. These centers are to work on a spectrum of short- and long-range R&D, and carry out crosscutting, multidisciplinary work on a variety of threats. To assist it in planning for these centers, TSA asked the NRC to hold a workshop to generate a broad range of ideas to draw on to help define the centers. This report presents the results of that workshop including the major ideas that emerged from the discussions.