It is often argued that at the root of the Taiwan question are the myriad differences in politics, ideology, identity, and economy between mainland China and Taiwan. Any prospect for its peaceful resolution, it seems, hinges on bridging those differences through economic and/or political integration. Although the Taiwan conundrum has much to do with wide-ranging cross-strait divergence, this article argues that it cannot be disconnected from one important commonality between Beijing and Taipei, namely, a cross-strait normative convergence on the Westphalian notion of state sovereignty. Encompassing an exclusionary understanding of final authority, territory, and identity, Westphalian sovereignty provides both Beijing and Taipei with a common meaning that Taiwan is an issue of sovereignty, central to their respective national identity and political survival and hence not subject to compromise. As a consequence, it argues that this common meaning is paradoxically responsible for much of the mistrust, tension, and deadlock in cross-strait relations. In order to find a long-term solution to the Taiwan impasse, we need to pay attention to this particular normative convergence as well as to the many differences across the Taiwan Strait.