The essay analyses a subject, that of the relationships between party systems and electoral rules, starting from the analysis of constitutional constraints imposed on the Legislature, more or less intense for different countries. Electoral systems and party systems influence each other. Any reconstruction in this respect cannot neglect an analysis of the technical aspects of each electoral system, but also numerous other variables, starting with the so-cio-cultural context in which political parties operate. Moreover, electoral systems cannot on their own have decisive effects in the structuring of political systems, being instead influenced by the latter, but only facilitating or restraining effects; taking into account that no electoral system is "better" than others, in any case and context.
Keywords: Sistemi elettorali, leggi elettorali, circoscrizione elettorale, formula elettorale, partiti politici; electoral systems, electoral law, electoral district, electoral formula, political parties.