The relationship between terrorist activities and states of emergency has never been explored in a cross-country perspective. This chapter is a first step to change that. Given that a terror act has been committed, what are the factors that lead governments to declare a state of emergency – or refrain from declaring it? And given that a state of emergency has been declared, what are the effects thereof? In this chapter, two world regions are analyzed: seventy-nine countries having Western-style constitutions and the member states of the Organization of Islamic Countries. We find that more terrorist incidents increase the likelihood of a state of emergency. Interestingly, emergencies are less likely to be declared in election years, supposedly because governments believe them to be unpopular. Once a state of emergency is declared, it generally leads to substantially more government repression. Finally, countries already under a state of emergency are more likely to suffer from additional terror attacks, challenging the effectiveness of states of emergency.