Despite the wide diversity of theories that offer explanations of the emergence of ethnic nationalism, most have two points in common. First, the factors inducing nationalism are located in the deep structural changes that have accompanied the process of modernization, the economic part of which is industrialization, the political one, state centralization. Second, the theories are compelling. In the areas affected by the complex package of factors described, those groups which possess the diverse raw materials for a nationalist movement should be expected, more often than not, to generate the leadership and mass support for such a movement. In other words, in the modern world mass based ethnic nationalist movements should be relatively commonplace.

From a brief survey of Mediterranean Europe two self-evident, but contradictory, conclusions can be drawn. First, nationalism has been overwhelmingly the most powerful political force to have operated in the area during the last 150 years or so. Indeed, almost all the states that open onto the Mediterranean are creations to a greater or lesser extent of a recent nationalist drive. Spain is not really an exception. Spain as a nation, in contrast to Spain as a state, had little reality before the mid nineteenth century.

Second, nationalism has been a feeble force. Despite the weight of the nationalist ideology in modern political thought, nationalism has produced very few nation-states in the strict sense of the word. Portugal is perhaps the only exception.