Reforms of decentralization are a visible trend in established democracies. While scholars often relate structural explanations to the territorial shift of authority, we argue that the why and when of these reforms can only be explained by an actor-based approach. Therefore, we embed decentralization in a framework of party competition and explain shifts of authority by electoral geographies. In this study we focus on the electoral determinants of asymmetric reforms. We argue that the logic of asymmetric reforms follows a simple set-relational logic that we outline, and we proceed to test our hypothesis with a newly compiled dataset of election results on the regional level and party positions of regional parties. The results are promising: the quantitative model not only predicts every asymmetric reform in our 12 country sample, but we additionally demonstrate a high consistency of the qualitative and quantitative findings. However, some counterfactuals remain unexplained.
