Putting the puzzle together: Why people join public interest groups

Why people join organizations, especially public interest groups, has been an unsolved puzzle. In this analysis, choice-based probability methods are employed to combine data from the 1980 National Election Study with comparable information about Common Cause members and to estimate models of the participation calculus that put the pieces of the puzzle together. The results demonstrate the primary importance of political interest and policy preferences for the membership choice. Citizens who are politically interested and have preferences that roughly match an organization's reputation find that associational membership has both greater benefits and lower costs for them than it does for others. Variations in the costs of communication — to the degree that they can be measured — are unimportant for the joining decision. An ability to pay is also irrelevant, regardless of educational attainment and despite members' high incomes. Organizational leaders deliberately keep the costs of membership low relative to most citizens' ability to pay; this encourages potential contributors to join in order to learn about the organization.I would like to thank Jeffrey Dubin for going beyond the realm of collegial obligation in providing programming and econometric assistance; Jeffrey Flint, for research assistance; and Kevin Grier, for wise advice. It should be emphasized, however, that all errors are exclusively the author's responsibility.