In the present research, we examined people's tendency to endorse or question belief in conspiracy theories. In two studies, we tested the hypothesis that the perceived morality of authorities influences conspiracy beliefs, particularly when people experience uncertainty. Study 1 revealed that information about the morality of oil companies influenced beliefs that these companies were involved in planning the war in Iraq, but only when uncertainty was made salient. Similar findings were obtained in Study 2, which focused on a bogus newspaper article about a fatal car accident of a political leader in an African country. It is concluded that uncertainty leads people to make inferences about the plausibility or implausibility of conspiracy theories by attending to morality information. Copyright © 2012 John Wiley & Sons, Ltd.