Abstract: The paper offers an analysis of modern research devoted to the qualification of the state of the modern political system in Spain. The author's attention is focused on the interpretation of systemic changes, the indicator of which was the activity of a new national party – "Citizens". The activities of the "Citizens" revealed the crisis of the traditional political system, based, in particular, on bipartisanship, within which two national forces dominated the country for more than 30 years – the conservative People's Party (NP) and the center-left Spanish Socialist Workers' Party (PSOE). Therefore, the activity of the Citizens Party in 2015-2022 is an illustrative example of the changes taking place in the country's political system. The author systematized the main directions of modern historiography, both Spanish and Russian, paying attention to the logic of their formation, the focuses of research interest, the source base and the methods used by specialists. The methodological basis of the work is based on the principles of historicism, objectivity, systematic analysis; historical and genetic method and comparative approach, which is due to the research logic of studying works on the transformation of the Spanish political system over time, and involves a comparative analysis of domestic and foreign literature. The conclusion is made about the similarity of methodology and sources; the "turn" in the study of Spanish Transit and the party-political system formed in 1975-1982 is defined – the transition from "modeling" to historical specifics. The main characteristics of the Spanish political system that exist in modern research are revealed, and the controversial prospects for the evolution of the system are noted. The author's qualification of the party system (the movement from bipartism to unstable multiparty system) dominates both modern historical works and political analysis. Modern researchers and analysts mainly paid their attention to the bright Podemos party, which is associated with its loud rhetoric and opposition to the constitutional foundations of Spain, but the activities of "Citizens", despite their activity in a crisis situation, turned out to be on the sidelines of research interest.