The study described in this article evaluates the effectiveness of methods of improving phonetic, grammatical, and syntactic skills in children with general speech underdevelopment in a bilingual environment. The method is based on a theoretical study of severe speech disorders, a structural analysis of linguistic samples, and a comparative study of the results of research by various scientists in an interdisciplinary discourse. An experimental study was carried out concerning the assessment of the effectiveness of speech therapy exercises for forming linguistic skills (phonetic-phonemic, morphological, word-formation, lexical, and syntactic) at different language levels in preschoolers with a general speech disorder in the context of bilingualism (Kazakh was considered the main language, and Russian was considered an additional language). The materials presented in this paper can be used to develop linguistic skills for various speech defects.