Assessment of first language adds important information to the diagnosis of language disorders in multilingual children.

Objective: 59% of Viennese day care children have a first language other than German. Lower proficiency in the second language German might be typical in multilingual settings, but might also be due to language disorder (ICD-10:F80 or comorbid). Diagnostic practise in Austria focuses on second language evaluation. This study describes a group of multilingual children with suspected language impairment at a specialized counselling hour and reflects the role of the first language in language evaluation.

Method: Linguistic evaluation (typically developed, ICD-10:F80, comorbid language disorder) and sociodemographic parameters of 270 children (time period: 2013-2020) are investigated. Linguistic results are reported according to primary diseases. For children without primary disease the relation between the linguistic evaluation and sociodemographic parameters is assessed.

Results: Overall, the children had 37 different first languages (74% were bilingual, 26% multilingual). The percentage of children with typical development and comorbid language development varied according to primary disease. Children without primary disease had higher chances of typical development the older they were at the examination, the earlier they produced first words, and if there was no heredity for ICD-10:F80.

Conclusions: Results suggest that evaluating the children's first language is useful since it contributes to understanding the individual language development at different linguistic levels, despite the heterogeneity of the children, and, thus, allows practitioners to recommend the best possible support.