It is well known that cross-linguistic interactions can exist between the two languages in a bilingual speaker’s repertoire. At the level of phonetics and phonology, this interaction may result in the transfer of a feature from one language to the other or the ‘merging’ of phonetic properties between languages. Although there are numerous studies of bilingual speakers which show such interactions, relatively little is known about the nature of transfer in communities of long-term bilingualism. The current study investigates phonological transfer of /r/ in Welsh-English bilinguals’ speech in north Wales. Specifically, it compares the influence of speaker gender, home language, and speech context on the production of /r/ in both English and Welsh in two communities which differ in the extent to which Welsh is spoken as a community language. It is commonly assumed that the alveolar trill [r] and alveolar tap [ɾ] are the variants of /r/ in Welsh. In English, the alveolar approximant [ɹ] is typical across Wales, but the trill and tap are reported in areas where a high proportion of the population speaks Welsh. Data in both languages were collected from 32 Welsh-English bilinguals (aged 16–18) via sociolinguistic interview and wordlist tasks. The sample was stratified equally by speaker gender, home language, and area (predominantly Welsh-speaking vs. predominantly English-speaking). The results show areal differences in the production of /r/ in both languages, which, I argue, could be attributed partly to differing social structures in the communities under investigation. Consequently, the results showed evidence of bi-directional phonological transfer, which is community-specific and influenced by a number of social factors.