The relation of science and democracy is an ancient conundrum that continues to generate public controversy. Whenever science produces an “inconvenient truth”—as Al Gore famously calls the science of climate change—democratic governments may be tempted to ignore or suppress it. And as scientists like to remind us, “You can’t vote on the laws of physics!” Natural scientists and their advocates often argue that the power of science in democracy depends on it remaining insulated from politics. Seen in this light, it is no wonder that many believe science and democracy tend to undermine each other. But another long tradition sees science and democracy as mutually reinforcing. Democracies depend on science for effectively addressing public problems, and many argue that science provides a model of rational democratic deliberation. These two conflicting interpretations each capture part of the story, but they neglect some of the most interesting questions, which concern changes in the meaning and purpose of science and democracy and how they shape each other in particular contexts. With regard to science, most scholars who study science and democracy now reject the long dominant “positivist” view of science as a formal, logical, socially insulated method for producing value-free knowledge. The ideal of value-free science remains popular in public life, but extensive research in the social sciences and humanities has shown how science is intertwined with social values, commercial pressures, and political decisions. That does not mean science merely reflects dominant interests, as caricatures of “social constructivism” assert, but it does open up difficult questions about how democratic citizens might shape the science that shapes their lives. With regard to democracy, mid-20th-century political scientists tended to conceive democracy narrowly in terms of popular elections and formal state institutions. Recent scholarship, in contrast, shows how social institutions and material practices of all kinds may become sites of democratic politics. Indeed, as democracy has increased in global popularity, its meaning has become increasingly diffuse and ambiguous; democracy offers both a rallying cry for social justice movements and a marketing slogan for global corporations. The relation of science and democracy involves a wide range of disparate phenomena, including science advice, science policy, public engagement in sociotechnical controversies, lay-expert relations, and the technical constitution of democratic citizens, not to mention the many specific concerns associated with issues like climate change, genetic engineering, or nanotechnology. Of course, “science and democracy” is not an established field of study, and nearly any piece of scholarship might be deemed relevant. This article is limited to works that directly address both science and democracy, understood as particular forms of knowledge and politics, respectively. This approach excludes many works that would fall under the headings “politics and science” or “democracy and knowledge.” Even within these limits, many important sources are missing, and readers should consult the bibliographies of the works cited here.