This chapter focuses on public support as a key resource that both terrorists and the state forces that oppose them must acquire and maintain if they are to achieve success. The general public is in the case of terrorist campaigns not merely a spectator on the sidelines but an active participant. The chapter provides an overview of research on the link between public support and (counter) terrorism. It deals with a discussion of how to understand the relationship between public support and (counter) terrorism. The chapter shows how public support is able to influence the efficacy of (counter) terrorist campaigns and what makes this factor so relevant to understanding success or failure in the fight against terrorism. It focuses on some of the various ways in which states can combat terrorism, using historical examples to illustrate how such measures can influence the distribution of popular support for the government and its non-state challengers.