The major purpose of this Special Issue is to provide the first comprehensive treatment of interest groups in Latin America. This first article provides background to this end by defining key terms and concepts; explaining the ubiquity of power groups, interests and interest groups in politics and government, and the fundamental elements of an interest group system, relating all this to past characteristics of Latin America's politics. Additionally, the article identifies the reasons for the dearth of studies of interest groups in the region and makes the case for the value of such studies. Drawing on this background, the article also sets out a heuristic for approaching the contributions to this volume and for developing a theoretical framework for the analysis of Latin American interest group systems. Copyright © 2013 John Wiley & Sons, Ltd.