This report provides a description and assessment of Internet-accessible databases relevant for social science research on terrorism. The body of this report details those websites that provide actual data, e.g., names of terrorist organizations and incidents of terrorist activity; several have search capabilities. These websites are maintained primarily by U.S. government agencies, non-U.S. research centers, and international organizations. An appendix to this report provides an extensive list of additional resources that provide commentary and analysis of terrorism events and trends. These resources are derived from the U.S. government, libraries, international agencies, government and private non-U.S. agencies and institutes, and academic-based domestic organizations.