Discussions of science and its relevance to public policy have recently taken center stage in political discourse, illustrating the values‐based nature of scientific policy decisions. This article uses an original data set of media coverage to examine the ways in which salience and media portrayals of scientific uncertainty affect the agenda‐setting process for scientific policy issues. We build upon two scholarly literatures by incorporating research on the use of science in the policy process into the study of policy diffusion among the American states. In doing so, we develop a framework for how media portrayals of scientific information can affect agenda setting. We test this framework on three scientific issues: Genetically modified food labeling, human papillomavirus vaccinations, and indoor tanning. Our results indicate that lawmakers introduce more legislation on salient issues, while higher reported levels of scientific uncertainty reduce the likelihood of bill introductions. This finding illustrates the potential impact of national media coverage as an information transmission mechanism and the necessity of treating policy characteristics as subject to change over time.