This chapter examines the political dynamics before the social unrest in Chile in 2019 by analyzing the evolution of the party system from a historical and longitudinal perspective. Focusing on the fifth political cycle, which began with the return to democracy in 1990, the chapter uses district-level election data and the effective number of parties (ENP) index to identify overlooked trends. The findings reveal three critical trends: (1) fragmentation within the party system began as early as 2009, which is well before what has previously been suggested, (2) a prominent leftward drift emerged as new parties sought to address the increasing demands for change, and (3) the system evolved asymmetrically, with fragmentation concentrating on the left and polarization deepening on the right. These shifts weakened the ability of the party system to maintain stability, amplifying vulnerabilities in governance. Incremental reforms further intensified fragmentation, which enabled abrupt changes in voter preferences and demands. By the mid-2010s, the party system had become too fractured to mediate societal tension, ultimately steering Chile toward the profound crisis of 2019. This analysis highlights the extensive influence of institutional changes on political stability and underscores the challenges of adapting democratic systems during periods of increased political diversity and polarization.