Legislative history research can be a difficult process, but finding historical information on federal rules and regulations can stump even experienced researchers. In Custodia Legis, the blog of the Law Library of Congress, recently published a guide, “How to Trace Federal Regulations,” that describes methods of researching administrative regulations and their history. Administrative rules and regulations are created by federal  agencies, boards, and commissions to implement the procedures for carrying out Congress’s legislative purposes. Congress delegates the authority to agencies to create regulations in enabling statutes. The guide discusses how to find the enabling legislation and an agency’s proposed and final rules. It explains the regulatory process in clear and concise language, for those who need a basic tutorial or a refresher, as well as where to find Authority Notes, which cite relevant sections of enabling statutes, and Source Notes, which often provide extensive information about a particular rule and why it was passed. The Notes also contain citations to regulations as originally drafted and amended and published for public comment in the Federal Register. Links to additional useful information on conducting administrative research are included.