Taiwan's gradual democratization has been celebrated as one of the most successful cases of political transformation, due to an initially smooth political transition from one-party authoritarianism to multi-party politics. Yet, this transition is incomplete and, especially since 2000 when the first non-Kuomintang president was elected, Taiwan has seen an intense and persistent politicization of its society. Institutional flaws are not enough to explain the shortcomings of Taiwan's democratic politics or those in other transitional democracies, the author argues. Rather, when an old dominant party like the Kuomintang continues to thrive even after the end of one-party rule, the process of political liberalization and transition contains within itself the seeds of structural politicization. This is, then, a study with empirical value - warning that extreme politicization is the main internal threat to the sustainability of Taiwan's democratic politics - but its analysis also applies to other transitional democracies around the world.