Why do governments and majority parties differ in the extent of control they have over the plenary agenda? In this article, I propose a theoretical model for explaining under what conditions parties choose to centralize and decentralize agenda control rules. I expect that the higher the party system concentration, the more extensive the majority control over the plenary agenda. This effect is likely to be the strongest if parties are stable and majority governments are the norm. I further expect that partisan factors exert their effects within the broader context of constitutional design. I test the theoretical argument through a detailed analysis of the evolution of agenda control rules in Denmark, France and Germany in 1945-2011 and in Estonia, Hungary and Poland in 1990-2011.
