Yolanda Ruiz de Zarobe is Associate Professor of Language and Linguistics at the University of the Basque Country. Her recent publications have focused on the acquisition of morphosyntactic aspects of English as a third language, multilingualism, and issues related to CLIL. She has recently co-edited the volumes Content and Language Integrated Learning: Evidence from Research in Europe (2009) and CLIL in Spain: Implementation, Results and Teacher Training (2010). Juan Manuel Sierra is Associate Professor of Language and Applied Linguistics at the University of the Basque Country. He has been involved in language teaching and teacher education for many years. He has published on CLIL, second and third language acquisition, foreign language teaching methodology, curricular design and multilingualism. His work has appeared in books, edited books and in various national and international refereed journals. Francisco Gallardo del Puerto has a PhD in English Studies and is Associate Professor of Language and Applied Linguistics at the University of the Basque Country. His publications have focused on multilingualism, the acquisition of phonological aspects of English as a third language, and the analysis of the effect of age on the learning of English as a foreign language.