This dissertation investigates the linguistic and social factors influencing the variable pronunciation of syllable-final /r/ in the Spanish variety of Alcalá de Guadaíra (Seville). In particular, this study examines the realizations of /-r/ from an innovative perspective, following Bybee's (2000, 2001, 2002) theory about lexical frequency in the diffusion of phonological change, according to which variation and linguistic change affect high-frequency words first. The data consist of 5,772 cases of /-r/ taken from a corpus of approximately 18 hours of semi-informal interviews with 36 native speakers that were statistically analyzed with Goldvarb 2001. In the first part of the analysis several linguistic constraints (i.e. phonetic context, position in the word, grammatical category, number of syllables, and stress) and social factors (i.e. age, education, and gender) were examined with the purpose of providing a general perspective of the phonological affecting /-r/. The second part of the analysis focuses on determining the role of word frequency in such processes. The results indicate that both linguistic and social factors are significant in explaining deletion of /-r/, as it is favored by all the following phonetic contexts other than obstruents and vowels, infinitives, word-final position, and stressed syllables, as well as by the youngest generation, the lower education groups, and females. Word frequency was also found be a significant factor: high-frequency items favor deletion of /-r/ and low-frequency words disfavor it. These findings show that /-r/ deletion in Andalusian Spanish is not random or categorical but that it can be accounted for by both linguistic and social factors, agreeing with usage-based approaches to phonological variation and change like that of Bybee.