The past decade has witnessed a fundamental reconfiguration of Spain’s party system. What was once a stable two-party structure has evolved into a more fragmented and polarized multiparty landscape. This presentation examines the political, institutional, and societal causes and consequences of this transformation. It situates the fragmentation of the Spanish party system within a broader context of democratic stress and highlights key developments such as the secessionist challenge in Catalonia, the emergence of coalition governance at the national level, and the rise of a radical right party for the first time in democratic Spain. The analysis explores how these changes have reshaped patterns of party competition and political polarization, and reflects on the implications of Spain’s experience for understanding the dynamics of party system change and representative democracy in contemporary Europe.