The two previous chapters examine how party competition structures mainland policy domestically and how China–U.S. relations constrain or expand Taipei’s policy space internationally. This chapter develops a theoretical framework—what I term the two-level punctuated-equilibrium theory of Taiwan’s mainland policy—by integrating the two triangular structures identified in the previous chapters. At the domestic level, the ruling party, opposition forces, and the public form a triangular arena of issue framing, where feedback loops of framing, public response, and policy adjustment generate oscillations in cross-Strait policy. At the external level, Washington, Beijing, and Taiwan form the WBT triangle, in which the shifting balance between U.S.–China cooperation and rivalry fundamentally shapes the boundaries of Taipei’s maneuverability. By integrating the two levels within the two-level game theory, the framework explains how Taiwan’s mainland policy evolves through periods of incremental adjustment punctuated by sharp shifts, reflecting the interaction of domestic partisan competition and international strategic dynamics. This chapter applies the framework to two contrasting cases: the Chen Shui-bian administration (2000–2008) and the Ma Ying-jeou administration (2008–2016). These cases illustrate how the dynamic interactions between the two triangular structures jointly produced punctuated-equilibrium patterns in Taipei’s mainland policy.