'This book represents a major contribution to the study of both lexical diversity and language development... [and] provides the most comprehensive and compelling study available to date of vocabulary measurement, including type-token ratios, number of different words, and word length. The innovative, empirically validated, and user-friendly measure of lexical diversity (VOCD - or simply D) that it proposes is based on deep understanding of mathematical models combined with rich background in language acquisition and language assessment. The culmination of fifteen years of cooperative research between David Malvern, Brian Richards, and their co-authors at the University of Reading, this study represents the best of inter-disciplinary research. In style, the book is both erudite and readable. It should be an invaluable source of reference for scholars and graduate-level students in general and psycho-linguistics, in first and second language acquisition, language education, and language pathology.' - Ruth A. Berman, Professor Emeritus, Department of Linguistics, Tel Aviv University

'David Malvern and his co-authors have developed a new and very promising approach to the study of lexical diversity and language development. Their statistical method is far more sophisticated than anything we have had in the past. This book will be of great interest to the developmental psycholinguistic community.' - Professor Jean Berko Gleason, Department of Psychology, Boston University