Christiane Bongartz is a professor of English linguistics at the University of Cologne. Her research covers a range of theoretical and applied issues in language acquisition in various contexts (L1, 2L1 and L2), with particular reference to the interaction between language internal factors and acquisitional context(s). Jacopo Torregrossa is a professor of multilingualism and second language acquisition at the Romance Department of the Goethe University of Frankfurt. His research interests focus on the interaction between linguistic, metalinguistic and cognitive abilities among bilingual children.