Linda Escobar is Associate Professor at Universidad Nacional de Educación a Distancia in Madrid, having received her PhD from Utrecht University, the Netherlands. She has written on theoretical linguistics and L1 and L2 acquisition. Her teaching centres on English grammar, semantics, and syntax, and she has been a Visiting Scholar at the University of South California, Massachusetts Institute of Technology, and the Universidad Autónoma de Barcelona.Vicenç Torrens is Associate Professor at Universidad Nacional de Educación a Distancia in Madrid, having received his PhD from the University of Barcelona. His research interests are the acquisition of clitic pronouns, tense, agreement, mood and aspect in first language, and language impairment. He was previously a Researcher at Massachusetts Institute of Technology and a Visiting Scholar at Harvard University.Teresa Parodi is a Lecturer at Cambridge University, having received her PhD from the University of Düsseldorf, Germany. Her research addresses first and second language acquisition, including early simultaneous and successive bilingualism, with a focus on the acquisition of grammar. She is also active in the dissemination of the results of research on bilingualism and multilingualism to wider, non-academic audiences in events and publications.