Tax competition is the quintessential example of policy interdependence. The general idea is that tax changes in one jurisdiction lead to similar changes in others. However, research has shown that institutional and political constraints limit competition. This article develops another argument: that socialization among policy makers attenuates competitive dynamics by setting limits to the extent of competition that is considered acceptable. Using fine-grained Swiss data and spatial econometric techniques, it shows that personal income tax rates are more strongly correlated among competitors that do not participate in the same intergovernmental organizations. This finding implies that, to some extent, the detrimental consequences of competition can be mitigated by fostering institutionalized forms of interaction among policy makers.