Because terrorism and counter-terrorism are highly significant issues in international relations and domestic politics, terrorism expertise are a valued asset in public policy. Using an innovative, mixed method approach, this study will explore which people and institutions are designated as in a variety of arenas, what impact their expertise have and address the question of whether there is such a thing as genuine expertise in terrorism and how we might identify it. It will measure, compare and contrast the prominence of different terrorism experts in different domains, including academia, the media, the internet, the criminal justice system and the national and the international policy community, and will analyse the historical and institutional development of the use of terrorism experts by courts, governments and the media. It will also explore the ideological and institutional origins and affiliations of terrorism expertise by investigating the various think-tanks and private research institutes which provide support and funding. The research will provide an empirically grounded evidence base that can better inform public debate and policy decisions. The overall aim is to better understand terrorism expertise and to enable academics and other research users to more effectively make use of research on terrorism.