Book excerpt: State tax systems have generally not changed dramatically over the last 50 years, yet they are facing profound challenges. Increased international trade, the advent of electronic commerce, evolving federal-state relations, and interstate competition are just some of the developments that will have a powerful influence on how states collect revenue. This collection of essays from leading tax scholars addresses a wide variety of issues concerning the major sources of state tax revenue and provides insight into what has worked in the past and what will or will not work in the future.