This course provides an overview of key aspects of second language acquisition (SLA) as it pertains to learning and using a second (L2) or an additional language along with one's first language (L1) in naturalistic contexts or instructed learning settings. We will discuss a variety of empirical and theoretical issues in SLA research such as the role of learners’ L1, linguistic universals, the nature of input, maturational and socio-psychological factors, all of which may lead to differential levels of success and performance in L2 acquisition. We will also explore a range of psycholinguistic issues central to the understanding of the complex nature of the bilingual mind as well as the cognitive effects of bilingualism (e.g., how the multi-language user represents and processes linguistic information; the relationship between bilingualism and executive functioning, attention, and communicative skills).