BRIAN RICHARDS is Emeritus Professor of Education at the University of Reading, UK. He has published widely in the fields of first and second language and language assessment and together with David Malvern is co-author of Lexical Diversity and Language Development published by Palgrave in 2004. H. MICHAEL DALLER is Senior Lecturer for Linguistics and English Language at the University of the West of England, Bristol, UK. He has edited and authored books, and published articles on migration and multilingualism, assessing and modelling vocabulary knowledge and on the measurement of bilingual language proficiency. DAVID MALVERN is Professor of Education, the University of Reading, UK. He has been Research Officer at the Royal Society, Visiting Professor at the Department of Educational Psychology, McGill University, and a European Union and British Council Consultant. PAUL MEARA began his research career studying the psycholinguistics of syntax, but soon realized that vocabulary acquisition interested him more. He now works in Swansea University, UK, where he runs a group of part-time PhD students, all working on a range of vocabulary-related research topics. JAMES MILTON is subject leader in Applied Linguistics at Swansea University, UK. His research focuses on vocabulary acquisition and measurement in foreign languages. Recently published works include Modelling and Assessing Vocabulary Acquisition (2007). JEANINE TREFFERS-DALLER is Professor of Linguistics at the University of the West of England, Bristol, UK. She has published widely in the field of bilingualism and language contact, in particular on code-switching and borrowing in French/Dutch contact in Brussels. She is a member of the Editorial Board of Bilingualism: Language and Cognition.