The course provides an introduction to second language acquisition research. The initial lectures define the scope of second language studies and demonstrate their relevance to linguistics, language pedagogy and intercultural communication, their relationship to other disciplines, such as linguistics and applied linguistics, psychology, psycholinguistics and neurolinguistics, social psychology and sociolinguistics, and discuss major issues in related fields of study, such as multiple and heritage language acquisition. Then the historical predecessors of second language acquisition studies are presented: behaviourism in psychology as well as structuralism in linguistics and the Contrastive Analysis Hypothesis. The cognitive revolution in the social sciences initiated by Chomsky is discussed and the influence Chomsky’s early ideas had on the emergence of second language acquisition as a separate field of study. The influence of Chomsky’s ideas is also shown in early second language acquisition research: Error Analysis and interlanguage studies, morpheme order studies and Krashen’s Monitor Model. As the field matures, the scope of interest broadens to include crosslinguistic influence at the cognitive, not only linguistic, level. Then, Chomsky’s Universal Grammar is discussed along with the controversies it raised in second language acquisition research and Cook’s multicompetence proposal. After that, major developments in psychology are presented. This discussion begins with early research in first language acquisition contradicting some of Chomsky’s early claims. Then information processing approaches are discussed along with the role of memory in second language acquisition, as well as emergentism and usage-based approaches. The students are also introduced to neurological foundations of first and second language processing. The discussion ends with an overview of findings on the role of age in second language acquisition.