The Impact of Political Parties, Interest Groups, and Social Movement Organizations on Public Policy: Some Recent Evidence and Theoretical Concerns

This article considers the direct impact of political parties, interest groups, and social movement organizations (SMOs) on policy, providing evidence for a "core" hypothesis and three others that refine or qualify it. The core hypothesis: all three types of organizations have substantial impacts on policy. The other three: (1) when public opinion is taken into account, the political organizations do not have such an impact; (2) parties have a greater impact than interest groups and SMOs; and (3) interest groups and SMOs will affect policy only to the extent that their activities provide elected officials with information and resources relevant to their election campaigns. The source of data is articles published in major sociology and political science journals from 1990 to 2000, systematically coded to record the impact of organizations on policy. The major findings include: political organizations affect policy no more than half the time; parties and nonparty organizations affect policy about equally often; there is some evidence that organizational activities that respond to the electoral concerns of elected officials are especially likely to have an impact.