Severe gender imbalances coupled with the stark income differences across countries are driving an increase in cross-border marriages in many Asian countries. This paper theoretically and empirically studies who marries whom, including how cross-border couples are selected, and how marital surplus is allocated within couples in the marriage markets of Taiwan (a wealthier side with male-biased sex ratios) and Vietnam (a poorer side with balanced sex ratios). Among the cross-border marriages that are predominantly made up of Taiwanese men and Vietnamese women, I find that Taiwanese men are selected from the middle level of the socioeconomic status distribution, and Vietnamese women are positively selected for cross-border marriages. Moreover, I show that changes in costs of cross-border marriage, incurred by immigration-policy changes and proliferation of matching services, also affect the welfare of Taiwanese and Vietnamese who do not participate in cross-border marriages by altering marriage rates, matching partners, and intra-household allocations.