This paper takes as its starting point a contact-induced grammatical innovation at the level of attributive predications that has been reported for various Romani speakers, in Mexico, Colombia, Argentina and the United States. Adopting a cross-disciplinary approach, we present evidence both from a historical study that documents individual and family itineraries in the Americas during the first half of the twentieth century and from a multi-sited ethnographic study on biographical narratives. These studies reveal the existence of close links among individuals from geographically distant localities. We suggest that, in the absence of normative linguistic institutions, complex multilingual practices seem to have modified grammar at the level of the bilingual speaker and ultimately of the network as a whole. More generally, by considering a less-studied population engaged in transnational mobile practices, we seek to illustrate how mobility allows for linguistic change to spread rapidly and widely.