A person exposed to a persuasive communication in the mass media sees this as having a greater effect on others than on himself or herself. Each individual reasons: “I will not be influenced, but they (the third persons) may well be persuaded.” In some cases, a communication leads to action not because of its impact on those to whom it is ostensibly directed, but because others (third persons) think that it will have an impact on its audience. Four small experiments that tend to support this hypothesis are presented, and its complementary relationship to a number of concepts in the social sciences is noted. The third-person effect may help to explain various aspects of social behavior, including the fear of heretical propaganda by religious leaders and the fear of dissent by political rulers. It appears to be related to the phenomenon of censorship in general: the censor never admits to being influenced; it is others with “more impressionable minds” who will be affected.