Discourse markers (DMs) are linguistic forms characterized by their use as conversation organizers or pause fillers (Fox Tree, 2010). Although used frequently in both speech and writing, DMs are not often taught in L2 classrooms, despite incorrect usage causing potential misunderstandings (Polat, 2011). Additionally, L2 learners have been observed employing DMs in their L2 either incorrectly or not at all (Vazquez Veiga, 2016). Notably, DMs used in L2 Spanish incorrectly are often false cognates with English DMs (Vazquez Veiga, 2016).This dissertation explores how speaker language similarity affects how "appropriately" first language (L1) French and English speakers use DMs in Spanish, their second language (L2), specifically to determine if the effects of false cognates are equally as present with typologically similar languages. In addition, this dissertation aims to determine if teaching DMs in a Spanish course can mitigate misunderstandings caused by inappropriate use and create more cohesiveness. This is measured by testing if a lesson on Spanish DMs is beneficial to students' performance on written assessments in a Spanish course. Both facets of this dissertation are carried out in two related, yet distinct studies.Using two learner corpora, L1 (French or English), cognate status, and proficiency level, as well as age and gender, as these can create differences in the frequency and patterning of DM use (Troncoso, 2022), were used to code data from the "Corpus Escrito del Espanol L2" (Lozano, 2022) and the "Corpus de Aprendices de Espanol" (Rojo & Palacios, 2016). To determine which of these has the most influence on DM appropriateness, statistical analyses were performed in RStudio (RStudio Team, 2020). Data suggest that while L1 and cognate status are important factors in determining whether a learner of Spanish will use a DM appropriately, a general linear model found that the only statistically significant predictor of DM use was proficiency level (p < 0.05), where less proficient speakers had fewer appropriate uses of DMs. This suggests that proficiency level is more influential than L1 similarity, but more data are needed to solidify this claim. I recruited participants from two sections of a fourth-semester, intermediate-level Spanish course at a university in New York State to test the second goal of this dissertation. One section served as a control group, and the other as an experimental group. Both groups took an identical pretest, and the experimental group received an explicit lesson on Spanish DMs that I designed. After, both groups took an identical posttest, which was a written assessment. Observations from the participants' responses suggest a positive correlation between the lesson on DMs, DM use, and performance on the assessment. However, statistical analysis did not yield any significant results. Therefore, more data are needed to make a definitive claim on whether teaching DMs can positively increase student performance in L2 (Spanish) classes.This dissertation offers considerations for how students acquire DMs in L2 Spanish, as well as implications for including them as language taught in an L2 Spanish class. Although no definitive claims can be made, this dissertation aims to contribute to discussions in the field about whether instructors should include DMs in world language curricula. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]