The nationalist question in Spain is the most complex problem and the most incertain challenge facing its politicians and state institutions, whose deficit of legitimacy in some territorial areas increases the weakness of the "united and indivisible" constitutional concept of the spanish nation and deepens the latent crisis of national conscience. Based on democraticity and modernity imperatives, putting an end to the old international isolation and maintaining the peninsular and european "staus quo", the Constitution of 1978, which instituted the "Estado de las Autonomias" - an open and evolutive model of internal distribution of political power, without resolving the major problem of the peripheral nationalisms, allowed for the emergence of several nationalist, autonomist and regionalist claiming agents and for a growing and open competion among them. The independentist posture, the assertiveness of particularisms, the violent ways of ETA and the international projection of the peripheral nationalisms, have weakened the country, creating an environment of internal tensions, that can forestall the unfinished structural process of the "Estado de las Autonomias". Externally, this situation induces a negative perception of spanish unity, undermines its international credibility as well as the legitimacy of its foreign policy decision makers. Therefore, the nationalist problematic in Spani has not only an obvious internal dimension, but also an evident external scope, given the fact that it questions the sovereignty of the Nation-state, on which system is still based International SocietyAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga