This paper investigates the reasons for different electoral performances of ethnoregionalist parties in Western Europe. The starting point of the research is provided by a short review of theoretical literature about the emergence and success of ethnoregional mobilization, by which some limits of existing explanations are highlighted. In particular the widespread vision of these parties as representatives of ethnic minorities seems unable to explain the cyclical pattern of electoral success of many of them and recent emergence of new ones in regions that are not provided with strong and visible elements of cultural distinctiveness. Ethnoregional parties - the argument goes - may also perform a role of challengers of major parties and attract portions of their disappointed electorate, politicising themes not directly related to the core ethnic issue, at least if and when some characteristics of the electoral competition allow that. The statistical analysis performed in the last paragraph confirms that these parties are sometimes able to act as catalysts of dissatisfaction towards established parties, and that several features of party competition are important explicative factors of ethnoregional vote, beyond the traditional identity and economic variables.