Based on field research conducted in the late 1920's, the Spanish dialectologist Tomás Navarro Tomás found the mountains of west-central Puerto Rico to be linguistically highly conservative. Among the phonological features Navarro Tomás associated with this geographical zone are the use of archaic word-final -i and -u, the distinction of syllable-final -l and -r, and a commitment to the velar rr that has distinguished Puerto Rican Spanish (Navarro Tomás, 1948). In Latin American Spanish, published in 1994, John Lipski suggests that "most of the strictly regional variation in Puerto Rican Spanish has been smoothed out, leaving the vertical sociolinguistic stratification as the most significant differentiator" (Lipski, 1994: 328). Based on a study of the five phonological features mentioned above, this paper investigates to what extent it is possible to say that regional dialectal usage continues to characterize west-central Puerto Rico, and to what extent this characterization is based precisely on the social conditions of language use in the region. The paper presents findings based on field research carried out between 1993 and 1997 in and around the community of Castañer. Linguistic data are based on recorded conversations with 60 males drawn from three different speaker samples.