Legislative professionalism and the demand for groups: The institutional context of interest population density

Do state interest group systems develop independently of the legislatures they lobby? The Energy-Stability-Area model developed by Gray and Lowery (1996) implicitly suggests they do. I argue that legislative professionalism conditions how group systems respond to environmental factors. As legislatures professionalize, their demand for information from lobbyists decreases. Groups are in this and other ways less effective in professional legislatures and more likely to exit a crowded group system. I model interest density with professionalism as a contextual variable. The results have implications for the number and mix of interests, the impact of lobbying regulations, and the consequences of legislative de-institutionalization.