By facilitating the flow of information in society, communications technology (CT; e.g., newspapers, radio, television, the Internet) can help terrorists to (i) spread their message, (ii) recruit followers, and (iii) coordinate among group members. However, CT also facilitates monitoring and arresting terrorists. This article formulates the hypothesis that a society’s level of CT is systematically related to terrorism. We introduce a simple theoretical framework, suggesting that terrorism first becomes more attractive with a rise in CT, but then decreases, following an inverted U shape. Accessing data for 199 countries from 1970 to 2014, we find evidence consistent with these predictions: terrorism peaks at intermediate ranges of CT and corresponding magnitudes are sizable. Our estimations control for a range of potentially confounding factors, as well as country fixed effects and year fixed effects. Results are robust to a battery of alternative specifications and placebo regressions. We find no evidence of a potential reporting bias explaining our findings.