The nature of interest groups and their variety in modern states is the central focus. How the interest group system represents public opinion in general and the circumstances that tend to make the interest group system more or less representative are presented. The problem of collective goods and participation in groups is also addressed. The chapter offers a typology of interest groups (sectoral, promotional, and institutional) and looks at how the tactics chosen by interest groups are affected by the resources of the group and the political environment within which the group exists. Pluralism and neocorporatism are contrasted. The chapter ends with detailed discussions of interest groups in France and Japan.