Major US federal regulatory decisions are developed and justified using regulatory impact analyses (RIAs) mandated by executive order. We examine the scientific citation activity in RIAs, a unique effort that we believe holds significant potential for understanding the use of science in policymaking. This paper reports preliminary findings from collecting and examining scientific citations in 104 RIAs from 2008–2012. We present evidence indicating that some agencies make extensive use of science in RIAs, that there is substantial variation in use across agencies, and show variation across journals and disciplines cited by regulatory agencies. Finally, we present analysis showing that regulatory policymakers make greater use of research published in highly cited scholarly journals. We conclude by outlining several future directions for research using these data.