In this article we synthesize theory and research from several areas of psychology and political science to propose and test a causal model of the effects of threat on political attitudes. Based in part on prior research showing that fear, threat, and anxiety decrease cognitive capacity and motivation, we hypothesize that under high (vs. low) threat, people will seek to curtail open-ended information searches and exhibit motivated closed-mindedness (one aspect of the need for cognitive closure). The subjective desire for certainty, control, and closure, in turn, is expected to increase the individual's affinity for political conservatism, insofar as resistance to change and adherence to authority figures and conventional forms of morality are assumed to satisfy these epistemic motives more successfully than their ideological opposites. Consistent with this account, we find in Studies 1a and 1b that putting people into a highly threatened mindset leads them to exhibit an increase in motivated closed-mindedness and to perceive the world as more dangerous. Furthermore, in Study 2 we demonstrate that a subtle threat manipulation increases self-reported conservatism (or decreases self-reported liberalism), and this effect is mediated by closed-mindedness. In Study 3, we manipulated closed-mindedness directly and found that high (vs. low) cognitive load results in a greater affinity for the Republican (vs. Democratic) party. Finally, in Study 4 we conducted an experiment involving political elites in Iceland and found that three different types of threat (to the self, group, and system) all led center-right politicians to score higher on closed-mindedness and issue-based political conservatism. Implications for society and for the theory of ideology as motivated social cognition are discussed.