||When couples with very different attributes marry, what are the rationales behind their decisions? This study examines how people evaluate their prospective partners, their motivations to marry, and the effects of attributes on the dynamics of marriage. The paper proposes a new theory which distinguishes intrinsic and extrinsic attributes of partners in the process of mate selection based upon which marital exchanges take place. The marriages between Chinese on the mainland and on Taiwan provide a unique opportunity to help construct the theory. Mainland China and Taiwan have been divided since 1949, creating two regimes that share a common culture but that have different socioeconomic and political systems. However, the recent interactions between the two has resulted in a significant number of interregime marriages. From two surveys on such marriages, the authors analyze the pattern of such marriages within the guidelines of the proposed theory. Empirical evidence from the surveys confirm the proposed theory. It is found that marriage typically occurs between Taiwanese male and a Chinese female, but the Taiwanese male tends to have higher extrinsic attribute values and the Chinese female is more likely to possess higher intrinsic attribute values. It can be logically argued that when the extrinsic attributes of the mainland brides are substantially improved due to the new opportunities introduced by the marriage, the temporary equilibrium of these interregime marriages will be upset. The proposed theory provides a new framework for both empirical investigations as well as further theory construction for studies of marriage, mobility, and social exchange.