This volume, first published in 1967, offers a new approach to the study of pressure groups, whose importance in the British political system has been increasingly recognised in recent years. Francis Castles seeks to throw light on this topic, firstly by examining the theoretical approaches to an understanding of their role in the political process and secondy by presenting a number of specific studies. For the first time, in one small volume, the reader can become acquainted with pressure groups in continental Europe, Scandinavia, the United States, the totalitarian countries, and the emergent nations. The study is comprehensive in itself and also an invaluable guide to more detailed work in this field of political science.