The scholarly debate on the role of public opinion in the foreign policy process of democratic states has been heatedly led between traditionalists at one pole and revisionists at the other. The former portray public opinion as fickle, incoherent, and ignorant, while the latter argue that publics are able to form coherent and meaningful opinions under certain conditions despite a lack of informational sophistication. The moot point most relevant to democratic theory, however, has concerned the influence of the public on foreign policy. Taking stock of the literature on the nature of public opinion and its impact in four important issue areas of foreign policy, this review concludes that public opinion 1) is not unstable or incoherent despite low levels of factual knowledge about foreign affairs, 2) is firmly situated within a complex framework of mediating actors and conditions at different levels of analysis, 3) exerts influence, particularly when issue salience is high, but to varying degrees depending on the issue area.