State constitutions are terribly important legal documents, but their interpretation is remarkably understudied (and, of course, highly undertheorized) in the academic literature. This review essay discusses Robert Williams’s welcome new book, The Law of American State Constitutions (Oxford University Press, 2009). After summarizing the content of Williams’s book, it discusses the normative significance of his work, focusing especially on his discussion of independent state constitutions and the positive theory of interpretation he advances. The essay concludes by highlighting some areas where the field of state constitutional law is in need of further advancement, including research that positions state constitutions within federalism and engages in serious institutional analysis.