It is important to emphasize the weaknesses of the economic approach.Because these models are abstract and formal, they may well leave out components of group formation, goal setting, and maintenance that arc not mere details but are integral parts of the political process. But this is only a potential criticism; the case is by no means prima facie. What is important and what is detail is a crucial distinction, but the fact that a model abstracts from detail to present a parsimonious formulation of a complex system is not sufficient cause for rejection.The burden of proof that some aspect of democratic politics (political culture,voting rules, or legislative institutions such as committees) is crucial to the process lies with the reader. The process of incorporation of the economic approach into mainstream political science is well begun, and extensions and corrections have been added. The economic approach is by no means the only tool useful for understanding interest group activity, but it is important. In this review we have tried to make it a more widely available one.