Contents 前言 Acknowledgments Abstract List of Abbreviations List of Tables List of Figures List of Appendices Introducing the Study 0.1 Introduction. 0.2 The Need for the Study 0.2.1 The Theoretical Need 0.2.2 The Methodological Need 0.2.3 The Pedagogical Need 0.3 Significance of the Study 0.3.1 Theoretical Significance 0.3.2 Methodological Significance 0.3.3 Pedagogical Significance 0.4 Outline of the Study 0.5 Summary PART I BACKGROUND Chapter I Literature Review 1.1 Introduction 1.2 The Trait and Interactionalist Approaches to Assessing L2 Vocabulary 1.2.1 The Trait Approach to Assessing Vocabulary 1.2.2 The Interactionalist Approach to Assessing Vocabulary 1.3 The Trait and Interactionalist Approaches: A Contrast 1.4 Previous Measures of L2 Lexical Performance 1.4.1 Lexical Variance 1.4.2 Lexical Density 1.4.3 Lexical Sophistication 1.4.4 Lexical Originality 1.4.5 Collocation 1.5 Previous Studies of the Relationship Between L2 Lexical Performance Measures and L2 Writing Quality 1.5.1 Relationship Between Lexical Variance Measures and L2 Writing Quality 1.5.2 Relationship Between Lexical Density Measures and L2 Writing Quality 1.5.3 Relationship Between Lexical Sophistication Measures and L2 Writing Quality 1.5.4 Relationship Between Lexical Originality Measures and L2 Writing Quality 1.5.5 Relationship Between Collocation and L2 Writing Quality 1.6 Problems in the Previous Studies of L2 Lexical Performance Measures 1.6.1 Lack of a General Framework in the L2 Lexical Performance Measures 1.6.2 Confusing Definitions of L2 Lexical Performance Measures …… PART II METHODOLOGY RART III RESULTS AND DISCUSSION PART IV CONCLUSION