The study of Spanish in contact with Wayuunaiki has received limited attention in generative and variationist analyses. In particular, the possible influence of this indigenous language on some parts of the Spanish language has not been investigated or has been only briefly addressed. This dissertation aims to fill this existing gap by studying two morpho-syntactic variables: (i) the distribution of null and overt subjects (NOS) as portrayed by the Null Subject Parameter and overt subject personal pronoun (SPP) expression as traditionally researched in variationist studies, and (ii) the issue of subject-verb agreement within the theory of features. To carry out these studies, we collected spontaneous data from 27 Wayuunaiki-Spanish bilinguals and five Spanish monolingual speakers. This Spanish monolingual group served as the vernacular benchmark. The NOS and SPP expression are among the most studied topics in Hispanic linguistics, but they have never been systematically researched in Guajiro Spanish. By analyzing these issues in our dissertation, we want to contribute new data to their study and to the properties and factors affecting them, in order to widen the knowledge of how they function in this Spanish language contact situation. In the generative analysis of the null/overt subjects we investigate whether the distinction that occurs in Wayuunaiki between stative and active verbs and the participants’ proficiency in Spanish have an impact on the distribution of NOS in Guajiro Spanish. In the variationist study, a number of independent variables widely believed to constrain variable SPP expression are factored into the investigation to find out how they behave in this particular language contact situation. These variables include person/number, TAM, switch reference, priming effects, etc. The second research topic is subject-verb agreement. This is only investigated from the generative grammar perspective, specifically by employing the concept of features to explain the nature of the subject-verb mismatches produced by the Wayuunaiki dominant Wayuunaiki-Spanish bilinguals. We specifically investigate whether the Spanish conjugation system poses a problem to the bilingual speakers’ ability to produce the native Spanish verb forms vis-à-vis the monolingual cohort and whether this ability is shaped by the participants’ proficiency in Spanish. The results of the three studies contribute to the field of Hispanic linguistics from three different perspectives. The study of NOS adds a new dimension to the pro-drop parameter: the possible role that Wayuunaiki’s double conjugation may play in the distribution of null and overt subject pronouns in Guajiro Spanish. The variationist study provides new data on the topic of SPP expression in a variety of Spanish which, in this specific case, has as contact language an understudied indigenous language. The analysis of the subject-verb mismatches that occur in Guajiro Spanish allows us to differentiate between the status of null and overt subjects with respect to subject-verb agreement and to differentiate between this contact variety and the Colombian vernacular benchmark.