As an ethnically heterogeneous but stable democracy, the United States is a puzzle for students of politics. According to the received wisdom of democratic theory, ethnic diversity is not conducive to stable government Indeed, the infrequency of ethnically heterogeneous but stable democracies suggests there is much to be said in favor of this proposition. 1 The United States, however, is a conspicuous exception to the general rule. Whereas ethnically based conflict is not foreign to the American political experience, the United States has been able to avoid the system-threatening consequences of heterogeneity known in other democracies. Moreover, of the handful of countries that are both heterogeneous and stable, America appears distinctive in the extent of its political integration, possessing an extraordinary ability to create the sentiments of political solidarity necessary to counteract the centrifugal forces of an ethnically diverse society. It is for the source of the United States’ power of political transformation, this capacity to change an ethnically heterogeneous mass into a politically consolidated and stable whole, that the present study seeks.