The authors propose that the high levels of support often observed for governmental and religious systems can be explained, in part, as a means of coping with the threat posed by chronically or situationally fluctuating levels of perceived personal control. Three experiments demonstrated a causal relation between lowered perceptions of personal control and the defense of external systems, including increased beliefs in the existence of a controlling God (Studies 1 and 2) and defense of the overarching socio-political system (Study 4). A 4th experiment (Study 5) showed the converse to be true: A challenge to the usefulness of external systems of control led to increased illusory perceptions of personal control. In addition, a cross-national data set demonstrated that lower levels of personal control are associated with higher support for governmental control (across 67 nations; Study 3). Each study identified theoretically consistent moderators and mediators of these effects. The implications of these results for understanding why a high percentage of the population believes in the existence of God, and why people so often endorse and justify their socio-political systems, are discussed.