1. Bio data of authors; 2. Introduction (by Jarvis, Scott); 3. Chapter 1. Defining and measuring lexical diversity (by Jarvis, Scott); 4. Chapter 2. From intrinsic to extrinsic issues of lexical diversity assessment: An ecological validation study (by McCarthy, Philip); 5. Chapter 3. Measuring lexical diversity among L2 learners of French: An exploration of the validity of D, MTLD and HD-D as measures of language ability (by Treffers-Daller, Jeanine); 6. Chapter 4. Validating lexical measures using human scores of lexical proficiency (by Crossley, Scott); 7. Chapter 5. Computer simulations of MRC Psycholinguistic Database word properties: Concreteness, familiarity, and imageability (by Crossley, Scott); 8. Chapter 6. Modelling L2 vocabulary learning (by Edwards, Roderick); 9. Chapter 7. Vocabulary acquisition and the learning curve (by Daller, Michael); 10. Index