IntroductIonContemporary societies, characterized by their complexity, are shaped by numerous social interests that must be present in the political system (Almond, 1958;Burdeau, 1982). These interests are the expression of citizens' demands on public affairs, which must be addressed by those in power (Bentley, 1983;Berry, 1977). These are also translated into the political system through specialized organizations, which traditionally have consisted of political parties. But interests are also conveyed through lobbies, in the form of organizations that develop activities aimed at public authorities in order to influence decisions that affect their interests.