Standing in a crowded room: Exploring the relation between interest group system density and access to policymakers

The numerous presence of interest groups may be a recipe for policy deadlock or, more optimistically, indicate the vibrancy of a political community. Population-ecology theory suggests that the number of interest groups active in a policy domain is relevant for strategies and political outcomes, such as policy access, and interest group density is expected to reduce access for individual organizations. Competitive pressures in dense domains necessitate groups to specialize to gain access to the policy access. We empirically assess this argument and indeed find lower levels of access in denser policy fields, moderated by specialization of organizations in lobbying. Furthermore, we identify important differences between mature (the Netherlands and Belgium) and young (Slovenia and Lithuania) interest group systems. These findings address theoretical concerns about the lack of linkages between micro- and macro-studies on interest representation.