In this paper first I discuss how changes in the EU affect regional interest groups and then I present three approaches for explaining their responses: economic, organizational, and institutional. I proceed with an empirical test of the political institutional variable -- specifically, political decentralization -- in a bivariate analysis of regional interest group strategies. This is done in a paired multi-sectoral comparison of French and Italian business associations. The investigation uses a most similar case design; by conducting the research in similar border regions of similar countries, I ensure adequate control over alternative explanatory variables. The project is also designed as a "crucial case" comparison. There is a distinct, but relatively small, difference in the degree of regional autonomy in Italy and France, which makes for a demanding test of the neo-institutional approach. The data support the hypothesis that the territorial distribution of power has a significant effect on the strategies of regional economic interest groups
