The article describes ways to face the regression of the first Russian language in a bilingual child`s speech. In the article considers the possibility of overcoming attrition in hereditary carriers by means of complex linguo-didactic diagnostics. Diagnostic data, as shown by the results of experimental training, can discern gaps and fill them in the course of bilingual education. Generally, metalinguistic skills are important in teaching bilingual children, which make it easy to transfer formed ideas from one language to another. This was previously well studied in the interaction of languages on an intercultural basis. Since the cognitive sphere is highly important in teaching a bilingual child, linguo-didactic diagnostics used in the learning process can be used as a tool for achieving educational results, language coordination, and a method of overcoming regression.

 Keywords: Children's bilingualism, language attrition, linguo-didactic diagnostics, language regression, language interference, metalinguistics skills.