Parties serve multiple functions: simplifying and structuring electoral choices; organizing and mobilizing campaigns; articulating and aggregating disparate interests; channeling communication, consultation, and debate; training, recruiting, and selecting candidates; structuring parliamentary divisions; acting as policy think tanks; and organizing government. Not only are parties one of the main conduits of political participation, they also serve to boost and strengthen electoral turnout. If mass membership is under threat, as many suspect, this could have serious implications for representative democracy. The first part of this chapter outlines theories of how party organizations respond to changes in their electoral environment and considers the implications that flow from this understanding. The chapter then looks at evidence for trends and patterns of party membership in the 1990s, comparing estimates based on official party records in the United States and Europe to survey data for fifty-nine countries from the World Values Study. On this basis, Chapter 7 goes on to examine the reasons why people join parties, based on the factors considered in earlier chapters, including the impact of societal modernization and political institutions at the national level, and the role of structure, agency, and culture in drawing individual citizens into public life.

Theories of Party Organization Change

In order to understand their role and functions, following the convention established by V. O. Key, parties can be divided into three hierarchical components: parties-in-elected-office, parties-as-organizations, and parties-in-the-electorate. Parties continue as vital sinews connecting the organs of government, particularly binding together the executive and legislature.