The transformation of Western European Party Systems was associated with the emergence of a new model of party organization: the cartel party. The cartel party differs from previous party models because it is increasingly less an agent of society, has interests on its own, depends on state subsidies and struggles to preserve the conditions under whihc it prospers by distorting electoral competition. Through such a distortion the cartel of parties resembles the behavior of oligopolistic firms.The purpose of this book is to investigate whether and to what extent patterns of inter-party competition resemble the functioning of oligo­polistic markets. The results of our comparative analysis reveal that there is a growing gap between voters' demands and party system's political supply. In addition to arguing the implications of these findings for the theory of responsible party government, this books shows that the growing gap between voters' demands and party systems' supply creates the condition for the rise of the parties of the New Extreme Right.