Basic Interests: The Importance of Groups in Politics and in Political ScienceA generation ago, scholars saw interest groups as the single most important element in the American political system. Today, political scientists are more likely to see groups as a marginal influence compared to institutions such as Congress, the presidency, and the judiciary. Frank Baumgartner and Beth Leech show that scholars have veered from one extreme to another not because of changes in the political system, but because of changes in political