Keywords: Spanish Legal System; Party System; Electoral System; Governability; Instability; Form of Government; New Political Parties.
The paper focuses on the principal changes that have taken place in Spain as consequence of the deep alteration of the political party system. This alteration become evident in the general elections held in December 2015 and June 2016. In the first part, the analysis focuses on the main elements of the Spanish political party system between1982 and 2015 and on the influence on his configuration by the electoral system. In the second part, the analysis focuses on the contrast between the stability and the governability that characterized the functioning of the Spanish democracy for almost the entire democratic period. The instability and the difficulties for the governability, originated by the new "map of political parties" existing in Spain at present, is the main point of final considerations.