I have attempted to depict the mainland policies of Taiwan's political parties and explain their convergent pattern using a rational-choice, spatial model as a tool for investigation. My conclusion is that democratization and competitive elections are the most important factors that account for the changes in the parties' positions toward mainland China. Based on that conclusion, one can project into the future what might happen if public preferences or electoral systems were to change. The issue of Taiwan's mainland policy is important both for its implications on security in East Asia and its challenge to the analyses of the academic world. This article has made a theoretical effort to unravel the dynamism of cross-strait interactions. Future effort in this direction is definitely needed.