The stability of a party system is seen as a desired, but not necessary, condition for a consolidated and well-functioning democracy. Since its transition from communism (1989), the Polish party system has been far from attaining stability or being recognized as institutionalized; however it has consistently ranked high in democratic consolidation. This article shows the changing trajectories of Polish party system over the last two-and-a-half decades and identifies the turning points for either temporary stabilization, or a return to again becoming chaotic. The dominance of axiological cleavages in party competition, high volatility and numerous party mergers, splits and the appearance of new organizations are just a few examples of the “stable instability” of these years. The last elections of 2015 have brought a new dimension to Polish party politics, i.e. one-party government, restoration and strengthening of the communist time division of the electorate and substantive changes which might undermine democratic principles.