Gene Grossman and Elhanan Helpman are widely acclaimed for their pioneering theoretical studies of how special interest groups seek to influence the policymaking process in democratic societies. This collection of eight of their previously published articles is a companion to their recent monograph, "Special Interest Politics". It clarifies the origins of some of the key ideas in their monograph and shows how their methods can be used to illuminate policymaking in a critical area. Following an original introduction to the contents of the book and its relationship to "Special Interest Politics", the first three chapters focus on campaign contributions and candidate endorsements - two of the tools that interest groups use in their efforts to influence policy outcomes. The remaining chapters present applications to trade policy issues. Grossman and Helpman demonstrate how the approaches developed in their monograph can shed light on tariff formation in small and large countries, on the conduct of multilateral trade negotiations, and on the viability of bilateral free trade agreements. They also examine the forms that regional and multilateral trade agreements are likely to take and the ways in which firms invest abroad to circumvent trade barriers induced by political pressures. The articles collected in this volume are required reading for anyone interested in international relations, trade policy, or political economy. They show why Grossman and Helpman are global leaders in the fields of international economics and political economy.