The past 18 months have seen a radical increase in incidents of jihadist terrorism within the United Kingdom from the Manchester Arena attack, to the Houses of Parliament, to London Bridge. As a result, there are renewed calls for a high-level national conversation about the causes of, and the responses to, this particular terrorist problem. This book identifies policy and research gaps from an evidence-based perspective it analyses what we know, what we dont know and what we need to know in relation to understanding and countering the jihadist terrorist threat. It provides readers with a synthesis of the knowledge and evidence that exists on each of the key topic areas, representing a distinctive and valuable resource for policymakers, academics and students. The contributors to the volume are leading international and national experts, from both the scholarly and policy-making communities, who are ideally placed to comment on the question of jihadist terrorism and the future of the threat in the UK.