Recent research conceptualizes language mindsets as a 'lens' through which learners view language challenges as either deficits of aptitude (i.e. entity beliefs) or opportunities to improve (i.e. incremental beliefs). Extending this meaning-system approach in an intercultural context, we proposed that language mindsets influence migrants' experience of intercultural interaction and cultural adaptation through language-based rejection sensitivity (RS) (i.e. the tendency to anxiously expect rejection from native speakers due to a lack of language proficiency). Two studies of 292 English-as-a-second-language speakers in Canada demonstrated that those who held or were primed with entity beliefs (vs. incremental beliefs) reported stronger language-based RS, which in turn predicted more intergroup anxiety towards members of the target language community, less perceived connectedness with the host country, and worse cross-cultural adaptation. These effects persisted after controlling for perceived language competence and length of residence, thereby highlighting the unique importance of language mindsets in predicting intercultural communication and cross-cultural adaptation. Migrants' settlement programmes that promote incremental beliefs may thereby lessen concern about social rejection and reduce their anxiety when using a second language.