This article discusses the various ways in which political concerns among government officials, scientists, journalists, and the public influence the production, communication, and reception of scientific knowledge. In so doing, the article covers a wide variety of topics, mainly with a focus on the U.S. context. The article begins by defining key terms under discussion and explaining why science is so susceptible to political influence. The article then proceeds to discuss: the government’s current and historical role as a funder, manager, and consumer of scientific knowledge; how the personal interests and ideologies of scientists can influence their research; the susceptibility of scientific communication to politicization and the concomitant political impact on audiences; the role of the public’s political values, identities, and interests in their understanding of science; and, finally, the role of the public, mainly through interest groups and think tanks, in shaping the production and public discussion of scientific knowledge. While the article’s primary goal is to provide an empirical description of these influences, a secondary, normative, goal is to clarify when political values and interests are or are not appropriate influences on the creation and dissemination of scientific knowledge in a democratic context.