The current study explores the influence of media use and interpersonal communication as antecedent variables to the illusion of knowing, the difference or discrepancy between perceived and factual knowledge. This study also examines the role of personal interest in science as mediating the relationship between communication activities and the illusion of knowing. A survey of undergraduate students showed interpersonal and mass mediated communicative actions, as well as interest in science, increased the illusion of knowing in the context of science communication. Support for the hypothesized mediation model was found, indicating that the effects of media use and interpersonal communication on the tendency to overestimate perceived knowledge about scientific issues occur indirectly through interest in science.