The transnational perspective emphasizes the persistence of immigrants' home country connections, yet existing research adds little to our understanding of the mechanisms by which cross-border ties are maintained. We use nationally representative data of immigrants in Spain to describe changes in their kin network and study how two characteristics, migration stage (whether kin already resided in Spain at the time of emigration and whether any kin remained in the birth country at the time of interview) and relationship-specific locations of kin (children, spouse, parents, siblings), influence the frequency of cross-border communication. We find an expansion in the total number of kin largely due to childbearing and marriage. The average fraction of migrants' immediate kin in Spain shifts from 6 to 41%. The presence of at least one kin in the birth country increases the frequency of cross-border communication, but with the exception of siblings, the presence of family already in Spain at the time of emigration does not. Siblings and parents were far more likely to retain a birth country presence, but they were less likely than spouses or children to be contacted daily. While these ties are generally long-lasting, communication wanes as immigrant embeddedness in the receiving country grows.