Contents -- Introduction -- Part 1 Theoretical Issues -- Chapter 1 Critical Period or General Age Factor(s)? -- Chapter 2 Phonological Acquisition in Multilingualism -- Chapter 3 Know your Grammar: What the Knowledge of Syntax and Morphology in an L2 Reveals about the Critical Period for Second/ Foreign Language Acquisition -- Part 2 Fieldwork in Bilingual Communities -- Chapter 4 The Influence of Age on the Acquisition of English: General Proficiency, Attitudes and Code-mixing -- Chapter 5 Age, Length of Exposure and Grammaticality Judgements in the Acquisition of English as a Foreign Language -- Chapter 6 English FL Sounds in School Learners of Different Ages -- Chapter 7 Maturational Constraints on Foreignlanguage Written Production -- Chapter 8 Variation in Oral Skills Development and Age of Onset -- Chapter 9 Learner Strategies: A Cross-sectional and Longitudinal Study of Primary and High-school EFL Learners.