The article studies way of making complex testing tools for bi- and polylingual children from the age of 3. The work focuses on determination of the balance degree of a child`s natural bilingualism; the researchers make an emphasis on the balance of language, speech and ethnocultural code switching. Tests have been taken into account other national languages and cultures (the combinations f.e. of Russian and German or Russian and Tatar ethnocultures), that allows to determine child`s communication competence in each language the same as his integration potential. Tests tasks correspond to the general age development of the tested child and stages of his language development. The innovation is offered by the Yelabuga Institute of the Kazan Federal University in co-operation with the International Methodological Council on Multilingualism and Cross-cultural Communication (including teachers from 38 countries all over the world).