The study of second language acquisition raises many questions which are of interest to both linguists and practitioners, such as future teachers of English. How do learners acquire a second language? What is the difference between first and second language acquisition? What determines speed and success in acquisition? What is the role of errors, cross-linguistic transfer, overgeneralization, fossilization, motivation etc. in the acquisition process? Can non-natives ever hope to achieve native-like competence? In this seminar we will try to answer these (and more) questions not only by reading key texts but also by analysing learner data hands-on.