Frontmatter -- Contents -- Acknowledgements -- Introduction -- 1 The Observable Phenomena of Second Language Acquisition -- 2 Early Linguistic Approaches to Explaining the Observable Phenomena of Second Language Acquisition -- 3 Sociolinguistic Approaches to Explaining the Observable Phenomena of Second Language Acquisition -- 4 Cognitive Approaches to Explaining the Observable Phenomena of Second Language Acquisition -- 5 The Approach to Second Language Acquisition Based on Universal Grammar -- 6 Parametric Variation and Transfer in Second Language Acquisition -- 7 Parametric Variation and Incompleteness in Second Language Acquisition -- 8 Parametric Variation, Staged Development and Cross-learner Systematicity in Second Language Acquisition -- 9 Parametric Variation, Variability and the Limits of the Explanatory Power of Universal Grammar in Second Language Acquisition -- 10 Explanations of Variability -- 11 Hypothesis Creation and Revision -- 12 The Development of Language Processing -- 13 Approaches to Learner Strategies -- 14 Towards a Model of Second Language Acquisition -- Bibliography -- Index