This special issue is comprised of a selection of studies presented at the Language Learning Workshop: Issues on Second Language Processing held in Barcelona, Spain in 2015. Organized by the Center for Brain and Cognition (Universitat Pompeu Fabra) and sponsored by the journal Language Learning, the workshop brought together prominent researchers in the field of language processing and bilingualism. Among them were Andrea Weber, Mara Teresa Bajo, and Narly Golestani. The contributions to this special issue are the result of the very fruitful discussions on various major issues of bilingualism. In particular, the nine articles included in this volume provide the most relevant experimental and theoretical evidence regarding second language learning as well as the linguistic and cognitive consequences of bilingualism across the lifespan. The contributions to this special issue are the result of the very fruitful discussions on various major issues of bilingualism. In particular, the nine articles included in this volume provide the most relevant experimental and theoretical evidence regarding second language learning as well as the linguistic and cognitive consequences of bilingualism across the lifespan.