Despite scientific consensus in the US that genetically modified (GM) foods are generally as safe as conventionally grown foods, the public remains skeptical about their safety. Extant research shows mixed results about the relationship between knowledge and attitudes when it comes to public opinion of GM foods in the US. This study uses data from the Pew American Trends Panel to examine the relationship between knowledge about GM foods and beliefs about their safety, in addition to what may be moderating these relationships. Results show that the relationship between knowledge and belief varies across different types of knowledge and that the effect of knowledge is moderated by perceptions of the immorality of genetic modification, rather than political or religious views.