This research project sought to explore the influence of English L2 on Spanish L1 in an environment where the L1 (Spanish) is the dominant language. Participants were recruited through voluntary response sampling at the University of Puerto Rico Secondary School (UHS). They completed a language survey on Google Forms that collected general information about their use and acquisition of English and Spanish and yielded data about the participants' age of exposure to Spanish and English, the frequency and domains where they use them, and their self-reported proficiency level in each language. After answering the language survey, participants completed an acceptability test on Google Forms that included fifteen items in Spanish with cross-linguistic influence from English and five fillers without cross-linguistic influence from English. They were prompted to indicate whether a sentence was acceptable or not in Spanish and to rewrite the sentences that they had classified as unacceptable so that they were acceptable. The quantitative analysis consisted of tallying their acceptable and unacceptable answers in percentages to facilitate comparison among groups and test the hypotheses that guided this study. After analyzing the data from the acceptability test from both a quantitative and a qualitative perspective, the results partially support the hypothesis that early exposure to and frequent use of English lead to higher percentages of acceptability in items with cross-linguistic influence. While no group consistently obtained the highest number of acceptable or unacceptable answers in all items with cross-linguistic influence, the group with early exposure to and less frequent use of English showed a tendency to behave the way the group with late exposure to and less frequent use of English was expected to behave (i.e., higher number of unacceptable than acceptable answers). [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.]