Can conspiracy theories be a source of social stigma? If it is true, it would follow that people may expect to be socially excluded when they express endorsement of conspiracy theories. This effect should be partially explained by the knowledge of the negative perceptions associated with conspiracy theories. In Study 1, inducing French internet users to write a text endorsing (vs. criticizing) conspiracy theories about the Charlie Hebdo shooting, led them to anticipate fear of social exclusion. This effect was mediated by anticipated negative evaluation of the self. In Study 2, inducing French internet users to imagine defending (vs. criticizing) conspiracy theories about the Charlie Hebdo shooting in front of an audience led them to anticipate fear of social exclusion. The effect was again mediated by anticipated negative evaluation of the self. To conclude, our findings demonstrate that conspiracy theories can be viewed as a source of social stigma.