Since 2000, when the DPP’s candidate Chen Shui-bian won the island-wide leadership election, Taiwan’s mainland policy has been formulated primarily by the two major political parties: the KMT and the DPP. I argue that the three key internal actors shaping this policy are the ruling party—whether the KMT or the DPP—the opposition party, and the public. Together, these three actors form a triangular structure whose dynamic interactions constitutes the core mechanism shaping the direction Taipei’s cross-Strait policy. Within this triangular structure, both parties compete continuously to influence the public by framing the unification–independence issue, the most controversial and politically explosive topic shaping Taiwanese’ party identification and voting preferences, in ways that mobilize support, undermine their opponents, reinforce their own preferred policy approaches and therefore influence the scope of policy change. The public, in turn, responds to these frames, exerting pressure on the ruling and opposition parties to recalibrate their strategies. This feedback loop—party framing, public reaction, policy adjustment—has defined Taiwan’s cross-Strait policy for more than two decades. This chapter examines the dynamics of issue framing between the major political parties in Taiwan’s cross-Strait policy since 2000.