Code-switching has been studied from different approaches, ranging from syntactical, sociolinguistic, psycholinguistic, phonetically and many others. One key area that phonetic studies have explore has been the production of VOT in Spanish-English bilinguals due to the differences across the languages. To understand how bilinguals co-activate their languages in code-switch productions, some studies have explored the effect of how cognates facilitate the co-activation of languages. The results of these studies have identified that bilinguals engage in VOT modulation when producing code-switching and that cognates tend to facilitate this process by triggering the activation of one language or the other in the production of VOT of voiceless stops. However, one outstanding question in the literature of phonetic studies regarding code-switching has been how cognates can trigger changes in the production of VOT of a following voiceless stop and how the different types of code-switching influence this effect. To study this, we conducted a study with three experiments with Spanish heritage speakers and, L2 learners of Spanish using a reading task. Participants read sentences in Spanish, English and Spanish-English code-switching, considering the variables of this study: VOT production, cognate status, and code-switching type. We found in our results a significant effect for VOT reduction in both speakers' groups when producing code-switched sentences. The results of the experiments suggest that cognate status and switch type are significant factors in modulating the production of VOT. This study show that code-switching can have an effect in the production of VOT in both Spanish heritage speakers and L2 learners of Spanish, and that previously unexplored variables like cognate status and switch type have an influence in this modulation process. Our experiment provides a venue for upcoming studies that could further explore this possible triggering effect of cognates in other experimental scenarios as well as updated approaches to explore the role of switch type in the process of VOT production. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]