This paper examines the process of European political integration. We start with a political-economy model of monetary policy, illustrating a general principle: economic integration requires setting up European institutions endowed with the authority to enact Europe-wide policies. On the other hand, when countries can take advantage of scale effects thanks to economic integration, the need for large countries is reduced. Thus increased economic integration reduces the need for political integration in Europe. To reconcile these views, we propose a model for the optimal allocation of prerogatives across levels of government. When the provision of public goods is characterized by cross-border spillovers, some centralization of policies is needed to internalize the externality. These gains from centralization must be traded-off against the costs from imposing the same policies upon heterogeneous groups. The optimal allocation of prerogatives results from this trade-off. Using our model as a benchmark, we analyze the institutional incentives at play for the allocation of political prerogatives in Europe and conclude that the EU has gone too far on most issues. "In areas which do not fall within its exclusive competence, the Community shall take action, in accordance with the principle of subsidiarity, only if and in so far as the objectives of the proposed action cannot be sufficiently achieved by the Member States and can therefore, by reason of the scale or effects of the proposed action, be better achieved by the Community." Article 3b. Treaty Establishing the European Community (Maastricht, 1991).
