This paper compares the scientific literature used most often by scientists to the scientific literature referenced on the English-language Wikipedia. Previous studies have raised concerns that editors of science-related articles on Wikipedia are biased toward easily available sources and underrepresent particular scientific fields. Most often, these studies examine references on Wikipedia only but make claims about how well or poorly Wikipedia represents the scientific literature as a whole. In contrast, the present study begins with the scientific literature. We use the Scopus database to identify the 250 most heavily used journals in each of 26 research fields (4620 journals in total), and estimate a variety of models to identify what makes these journals more or less likely to be cited on Wikipedia. We find that, controlling for impact factor and open access policy, Wikipedia over-represents journals from the Social Sciences, and under-represents journals from the Physical Sciences and Health Sciences. An open-access policy is not associated with increased Wikipedia presence. The most significant predictor that a journal will be cited on Wikipedia is its impact factor.