Vocabulary richness, including lexical diversity and use of rare words, has an important role in assessing proficiency, diagnosing progress and testing theory in the study of language development. This book reviews different methods for quantifying how vocabulary is deployed in spontaneous speech and writing, before introducing an alternative approach which can assess overall lexical diversity, measure morphology development and compare the development of different word classes. The new approach is illustrated by its application to first and second language learners.

DAVID D. MALVERN is Professor of Education, University of Reading, UK. He has been Research Officer at the Royal Society, Visiting Professor Department of Educational Psychology, McGill University, and European Union and British Council Consultant.

BRIAN J. RICHARDS is Professor of Education, University of Reading, UK, and for seventeen years was an associate editor of the Journal of Child Language

NGONI CHIPERE is Lecturer in Language Arts, University of the West Indies in Barbados, and author of Understanding Complex Sentences: Native Speaker Variation in Syntactic Competence published by Palgrave in 2004.

PILAR DURÁN gained a PhD at Boston University and was Research Officer, University of Reading, UK, before becoming Business Development Manager at Eurobios.