The aim of this review article is to introduce the issue of bilingualism and the diagnostic process of developmental language disorder in bilingual children in the context of current scientific knowledge. With regard to the geopolitical situation, it can be stated that the number of bilingual patients of Clinical Speech Therapists is increasing. Understanding the specifics of bilingual development, and knowledge of diagnostic options in the Czech language environment is an important prerequisite for the implementation of evidence-based practice. A Clinical Speech Therapist should be able to apply different approaches to diagnosis, according to the type of bilingualism, and to use dynamic diagnostics and available tools for assessment of both languages. Understanding the differences in bilingual language development, and the impossibility of applying monolingual norms is absolutely crucial.
