At the close of the 20th century, Spain underwent rapid demographic change, as it went from being a nation of emigrants to becoming a nation of immigrants. With the aim of better understanding the mechanisms behind dialectal accommodation, this dissertation asks what effect this situation of dialect contact has had on the language attitudes and language use of Dominicans in Madrid, one of the largest Latin American communities that have resulted from this demographic shift. The linguistic variable under study is the Santo Domingo category /s/ (Madrid Spanish /s/ and /θ/), which is the site of three differences between the two dialects that vary in terms of both social salience and linguistic complexity (allophonic vs phonemic differences, new feature adoption etc.). Through sociolinguistic interviews, this study collects data related to this category, and compares the acoustic correlates (spectral mean, spectral variance, segment duration, and mean intensity) of data from Dominicans in Madrid with those of Dominicans in Santo Domingo and Spaniards in Madrid. Additionally, the study examines attitudinal data, gathered from surveys and during interviews, which help to better understand participant experiences in Madrid, and their reasons for accommodation/non-accommodation towards the Madrid Spanish variety. Findings support the perspective that the accommodation mechanism is at least partially an automatic reflex in that, in absence of linguistic or social motivators that would constrain it, speakers are likely to converge. In this case, Dominicans in Madrid converge on the least socially salient of the differences between the two dialects ([s] vs [s̺]), regardless of social network, class, race or any other socio-demographic factor under study. On the other hand, final /s/ reduction rates are constrained by multiple social factors including the size of migrants’ social networks within the Dominican community. Finally, as survey and interview data suggest that large parts of the Dominican community live in a context of social marginalization from majority Spanish society, and find both social and economic resources within the Dominican and Latin American migrant communities, it follows that, the non-adoption of [θ], a highly salient feature that is associated with Spain, is almost unanimous among participants.