In the last few decades many studies have been carried out on the Spanish variety that is spoken in the Andean region of Peru. Researchers tend to attribute its innovative syntactic, morphological, phonological and semantic features to language contact with Quechua. I chose to analyze the Spanish discourse marker pues, which in Andean Spanish presents a different syntactic distribution and alternative functions such as that of obviousness. In order to show the different distribution and functions in Andean Spanish, I conducted thirty seven interviews and later contrasted them with randomly obtained speeches from Argentina, Mexico and Spain. Furthermore, I wanted to compare the Spanish from bilingual speakers from this Andean region to the Spanish from monolingual speakers from a coastal, non-Andean region. Therefore, I interviewed seventeen Spanish-Quechua bilinguals and twenty Spanish monolinguals. I selected the interviewees from one of two regions -one monolingual and one bilingual. Each region had previously suffered devastating earthquakes that caused severe damage and killed many people. I chose these towns because I wanted to elicit the use of pues meaning obviously. I asked questions related to these earthquakes that were answered in a very similar way among both monolingual and bilingual speakers. The fact that this pattern occurs not only in the bilingual area but also in the monolingual one weakens the Quechua interference hypothesis greatly. My sample of thirty seven speakers showed that this specific word is highly preferred by the middle class from both linguistic groups. This completely turned pues from a bilingual marker into a social class marker. This phenomenon can also be observed across languages since often times social classes tend to segregate themselves linguistically by using their own particular language features. Finally, throughout the whole dissertation I presented two opposing standpoints in the case of Andean pues: the theoretical framework supporting the hypothesis that Andean pues is the result of non-contact language-specific internal changes and grammaticalization, and the theoretical framework supporting the hypothesis that Andean pues is the result of language convergence between Quechua and Spanish. At the end of this dissertation the first hypothesis was accepted and the latter rejected; thus, I concluded that Andean pues is the result of Spanish internal changes influenced by social factors.