This book outlines the study of how people learn a language other than their mother tongue. It is designed to make the essentials of this rapidly expanding field as accessible as possible.

1.Introduction: describing and explaining L2 acquisition -- 2. nature of learner language -- 3. Interlanguage -- 4. Social aspects of interlanguage -- 5. Discourse aspects of interlanguage -- 6. Psycholinguistic aspects of interlanguage -- 7. Linguistic aspects of interlanguage -- 8. Individual differences in L2 acquisition -- 9. Instruction and L2 acquisition -- 10. Conclusion: multiple perspectives in SLA.