It is often assumed that there is a trade-off between civil rights and national safety although the association is theoretically ambiguous. This paper therefore explores this association by estimating the effect of degrees of freedom of expression on the risk of terrorist attacks. We first note that different theoretical arguments support both a positive and negative association between freedom of expression and terrorism. We explore this association empirically in a large panel of 162 countries observed between 1970 and 2016. Distinguishing between media freedom and discussion freedom, and separating democracies and autocracies, we find that discussion freedom is unambiguously associated with less terrorism in democracies.