Is it possible to differentiate multilingual children and children with Developmental Language Disorder?

The language profiles of monolingual children with Developmental Language Disorder (DLD) and typically developing multilingual children can overlap, presenting similar paths and delays in learning specific aspects of language in comparison with typically developing monolingual children of the same age. • In an increasingly multilingual society, it is essential to develop guidelines and tools for differentiating the two populations, avoiding both under- and overdiagnosis of language disorders in multilingual children. • Many multilingual children have a narrower vocabulary compared with monolinguals of the same age. Therefore, grammatical features are considered more reliable clinical markers of a possible disorder. • Clinical markers for children with DLD are language-specific. For example, in English-speaking children with DLD, verb endings may be omitted, as in “*Mary cook it”. For Italian or French children with DLD, a reliable marker is the realisation of certain pronouns, as in Mary lo cucina, “Mary it cooks”, with omissions or substitution of the pronoun lo depending on age. • Despite similarities between multilingual children and children with DLD, it is possible to distinguish between the two groups after multilingual children have at least two years of exposure to their second language (L2). • Multilingual children can learn their L2 fully, while this is generally not the case for monolingual children with DLD; however, children’s success in learning their L2 depends on length of exposure to the language, the type of multilanguage experience, and the structural relatedness of the two languages.