IntroductionBeing able to speak more than one language is proving to be a valuable skill in modern society. Many children around the world are at least bilingual, leaving many American parents wondering whether they, too, should learn to speak another language. While this debate is still ongoing, many adults are looking to learn a second language to both communicate with a new customer base and gain higher status within a business context. Most Americans learn a second language in adulthood. Many public schools do not begin teaching a second language until high school, and all college students must study a foreign language in order to graduate from college. Another population in the United States that is learning a second language is those who have immigrated from other countries, particularly Mexico. Most of these immigrants who are learning are adults, their children will not have to deal with learning a second language because they will most likely learn two languages, English and Spanish. For the purposes of this article, I have defined adulthood as including any person who is eighteen years of age or older, because there is so little research on language learning in early adulthood compared to middle or late adulthood. It is not possible to find studies on particular divisions of adulthood that have been verified by subsequent research studies, so I have included research on all ages of adulthood. In this article I will discuss major aspects of the research literature that separate second language learning by adults from that of natural bilinguals, including full immersion in the language, biological and neurological factors, the structure of both the native language and of the second language. , age of acquisition...... middle of paper ....... Journal Of Experimental Psychology: Human Perception And Performance, 34(5), 1305-1316. doi:10.1037/0096-1523.34.5.1305Lemhöfer, Kristin, Dijkstra, Ton, Schriefers, Herbert, Baayen, R. Harald, Grainger, Jonathan, & Zwitserlood, Pienie. (2008). Influences of native language on word recognition in a second language: A megastudy. 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, & Rodríguez-Fornells, Antoni. (2010).as anchors: Known words facilitate statistical learning. Experimental Psychology, 57(2), 134-141. doi:10.1027/1618-3169/a000017Abrahamsson, Niclas, & Hyltenstam, Kenneth. (2008). The robustness of attitudinal effects in near-native second language acquisition. Second Language Acquisition Studies, 30(4), 481-509. doi:10.1017/S027226310808073X