The events of September 11th have led to massive increases in personal, commercial, and governmental expenditures on anti-terrorism strategies, as well as a proliferation of programs designed to fight terrorism. These increases in spending and program development have focused attention on the most significant and central policy question related to these interventions: Are these programs effective? To explore this question, this study reports the results of a Campbell Collaboration systematic review on evaluation research of counter-terrorism strategies. Not only did we discover an almost complete absence of evaluation research on counter-terrorism interventions, but from those evaluations that we could find, it appears that some interventions either did not achieve the outcomes sought or sometimes increased the likelihood of terrorism occurring. The findings dramatically emphasize the need for government leaders, policy makers, researchers, and funding agencies to support both outcome evaluations of these programs as well as efforts to develop an infrastructure to foster counter-terrorism evaluation research.