Science communication has been historically predicated on the knowledge deficit model. Yet, empirical research has shown that public communication of science is more complex than what the knowledge deficit model suggests. In this essay, we pose four lines of reasoning and present empirical data for why we believe the deficit model still persists in public communication of science. First, we posit that scientists’ training results in the belief that public audiences can and do process information in a rational manner. Second, the persistence of this model may be a product of current institutional structures. Many graduate education programs in science, technology, engineering, and math (STEM) fields generally lack formal training in public communication. We offer empirical evidence that demonstrates that scientists who have less positive attitudes toward the social sciences are more likely to adhere to the knowledge deficit model of science communication. Third, we present empirical evidence of how scientists conceptualize “the public” and link this to attitudes toward the deficit model. We find that perceiving a knowledge deficit in the public is closely tied to scientists’ perceptions of the individuals who comprise the public. Finally, we argue that the knowledge deficit model is perpetuated because it can easily influence public policy for science issues. We propose some ways to uproot the deficit model and move toward more effective science communication efforts, which include training scientists in communication methods grounded in social science research and using approaches that engage community members around scientific issues.