The book focused on science and techlogy challenges associated with our nation's need to detect, prevent, protect against, and respond to terrorist attacks involving Radiological and Nuclear, Chemical, and Biological threats. While the organizers and participants of this workshop recognize that the threat of terrorism is extremely broad, including food and water safety as well as protection of our public infrastructure, we necessarily limited the scope of our discussions to the principal weapons of mass destruction. In order to set the stage for the discussions of critical science and techlogy challenges, the workshop began with keyte and plenary lectures that provided a realistic context for understanding the broad challenges of countering terrorism. The plenary speakers emphasized the sociopolitical complexity of terrorism problems, reinforced the need for basic research in addressing these problems, and provided critical advice on how basic research can best contribute to our nation's needs. Their advice highlighted the need to: Invest Strategically - Focus on Cross-Cutting Research that has the potential to have an impact on a broad set of techlogy needs, thereby providing the greatest return on the research investment. Build Team Efforts - Countering terrorism will require broad, collaborative teams. The research community should focus on: (1) Research Environments and Infrastructures that encourage and enable cross-disciplinary science and techlogy teams to explore and integrate new scientific discoveries and (2) Exploring Relationships with Other Programs that will strengthen connections between new scientific advances and those groups responsible for techlogy development and implementation. Consider Dual Use - Identify areas of research that present significant Dual-Use Opportunities for application to countering terrorism and other complementary techlogy needs.