Formerly Mastering Statutory Interpretation, this third edition has been updated and expanded to reflect the growing number of Leg-Reg classes in the law school curriculum. The text explains the legislative process; describes the difference between bills, acts, statutes, regulations, and guidance documents; explores the sources of meaning and the theories of interpretation; explains the linguistic and policy-based canons of interpretation; and introduces the administrative state. The book's organization starts with the enactment of an act, turns to codification, moves to interpretation, and concludes with agencies. The interpretation section begins with the most relevant sources of meaning—intrinsic sources, such as text—before moving to the next most relevant—extrinsic sources, such as legislative history—and concluding with the policy-based sources, such as the rule of lenity. Throughout, the text refers to the major cases in each area of study to coordinate with the major textbooks in the field. The book also includes a running hypothetical to help students better implement what they are learning. Finally, each chapter provides a concise roadmap and summary to introduce and encapsulate the most important material in that chapter.