IntroductionBeing able to speak more than one language proves to be a valuable skill in modern society. Many children around the world are at least bilingual, leading many American parents to wonder if they too should learn to speak another language. Although this debate is still current, many adults seek to learn a second language, either to communicate with new customers or to achieve a higher status within a company. Most Americans learn a second language as adults. Many public schools do not begin teaching second languages ​​until high school, and all students must study a foreign language to graduate from college. Another population in the United States learning a second language is immigrants from other countries, particularly Mexico. Most of these immigrant learners are adults, their children will not have to learn a second language because they will most likely learn two languages, English and Spanish. For the purposes of this article, I have defined adulthood to include anyone who is eighteen or older, because there is very little research on language learning in early adulthood by relation to middle or late adulthood. It is not possible to find studies on particular divisions of adulthood that have been verified by subsequent research trials. So I included research on all ages of adulthood. Throughout this article, I will discuss key aspects of the research literature that separate second language learning in adults from that of naturally bilingual people, including total language immersion, biological factors and neurological, the structure of the mother tongue and the second language. , age of acquisition...... middle of article....... Journal Of Experimental Psychology: Human Perception And Performance, 34(5), 1305-1316. doi:10.1037/0096-1523.34.5.1305 Lemhöfer, Kristin, Dijkstra, Ton, Schriefers, Herbert, Baayen, R. Harald, Grainger, Jonathan and Zwitserlood, Pienie. (2008). Influences of the mother tongue on word recognition in a second language: a mega-study. Journal of Experimental Psychology: Learning, Memory and Cognition, 34(1), 12-31. doi:10.1037/0278-7393.34.1.12Cunillera, Toni, Càmara, Estela, Laine, Matti and Rodríguez-Fornells, Antoni. (2010) as anchor points: known words facilitate statistical learning. Experimental Psychology, 57(2), 134-141. doi:10.1027/1618-3169/a000017Abrahamsson, Niclas and Hyltenstam, Kenneth. (2008). The robustness of aptitude effects in near-native second language acquisition. Studies in Second Language Acquisition, 30(4), 481-509. doi:10.1017/S027226310808073X