This e-Case documents the social issue of cross-border relationships in Hong Kong. Since Hong Kong’s handover to the People’s Republic of China in 1997, mainland residents are allowed to visit the territory with less travel restrictions. Adding to more frequent Hong Kong-mainland economic exchanges, there had been a notable rising trend of cross-border familial relations. Since the handover, more than 388,000 cross-border couples have married in either Hong Kong or on the mainland, which accounted for 16 per cent of the total number of households in Hong Kong. This e-case introduces students to the background of this phenomenon as well as relative government policies including the One Way Permit Scheme.