This dissertation explores subject pronoun expression (SPE) in Palenquero Spanish (PL Spanish) and Palenquero Creole (PL Creole), two languages that have coexisted for centuries in San Basilio de Palenque (Colombia), share most of their lexicon, but differ in their grammar. Crucially, this study investigates how the contact between them and the context of the acquisition of the second affect SPE in both languages. In this respect, this variationist study draws on the analysis of spoken data to examine the linguistic and extra-linguistic variables that constrain SPE in PL Creole and PL Spanish. The sample includes four different groups that represent the tendencies found in the community. The first group is composed of older bilinguals who are traditional speakers of the creole. The second is made up of middle-aged bilinguals who represent the first generation that benefited from learning this minority language in the school as part of the process of revitalization. The third one corresponds to young learners of Palenquero who are acquiring it as a second language. The last group includes young heritage learners of the creole who have grown exposed to this since early ages, but it is in the school where they are learning to use it as a means of communication. The analysis of SPE in the creole revealed that despite it is a non-null-subject language, the use of null subjects is more than marginal and follows different patterns depending on the group of bilinguals. The differences across groups do not point to the rates of overt and null subjects found in each of them, but instead, to the variables, rankings, and factors that each group selects. The sociolinguistic behavior observed in the youngest groups suggests a simplification of constraints in contrast to the group of older traditional bilinguals. Overall, the differences found across groups may be attributed to the persistent difficulties that heritage and second language learners experience when dealing with structures that involve more than one linguistic module (i.e., the interface hypothesis; Sorace & Filiaci, 2006) and the change that the creole is undergoing as part of the process of revitalization. In a parallel fashion, the analysis of SPE in PL Spanish also revealed strong differences across groups attributed not only due to generational causes but also to the way as the creole has been learned. Simplification of constraints in PL Spanish is in consonance with that found in the creole, especially in the youngest groups. Although the variables that constrain SPE in both languages differ, the lack of relevance given to the discourse variables in PL Spanish resembles that of the creole. Overall, both languages show a mutual effect due to their contact and context of the acquisition of the creole. In this line, PL Creole helps to preserve the high rates of overt subjects, and PL Spanish may be the cause for the considerable rates of null subjects in PL Creole (a non-null subject language). A comparison between PL Spanish with a sample taken from Cartagenero Spanish showed high rates of overt subjects in both varieties. Those rates allowed us to place them at the top of those dialects of Spanish distinguished by the highest numbers of overt subjects. Additionally, the patterns observed in both varieties also suggest that they are undergoing strong generational changes possibly in direction to the alignment with other Caribbean varieties. Besides that, similarities between the older groups of both varieties suggest the existence of an old dialectal zone that might have been distinguished by a high rate of overt subjects. The findings of the present dissertation outline the importance of combining language contact and second language acquisition as a powerful tool to understand how bilinguals deal with variation in contexts of intense contact and different acquisitional patterns. Likewise, this study highlights the usefulness of applying the variationist method in diverse groups of bilinguals to inform processes of linguistic revitalization. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]