Background. According to various sources, about half of the world's population speaks two or more languages on different levels. The steady growth of bilingual and multilingual populations through migration and learning of foreign languages, on the one hand, and the real threat of indigenous languages extinction, on the other hand, put the comprehensive study of bilingualism and multilingualism in a number of important social issues and interdisciplinary scientific problems.

Objective. The paper aims to analyze and summarize the results obtained in the research of the bilingualism impact on cognitive processes and individual characteristics in order to identify the possible advantages of bilingualism and the difficulties associated with them.

Results. The phenomenon of Russian national bilingualism and its specific features in some republics of the Russian Federation is considered. A variety of socio-cultural contexts in which bilingualism and multilingualism are studied justifying the need for an interdisciplinary approach to the research issues is presented. The theoretical and analytical review of the research of bilingualism influence on cognitive processes, personal characteristics and relationships with ethno-cultural identity is carried out. The areas in which bilingualism can provide benefits are considered, and the risks associated with the possession of several languages for the individual and for society are analyzed. The results of the bilingualism influence on cognitive processes and personal characteristics are contradictory and are determined by the attitudes of researchers and some factors and additional variables that are difficult to control due to various methodological problems. The necessity of interdisciplinary interaction in research the impact of multilingualism on various individual and social processes is shown.

Conclusion. Bilingualism and multilingualism are neither an advantage of the cognitive functioning and personal development of the subject, nor for society. There are additional conditions determined both by the individual situation of development and by the socio-cultural context. If taken into account they can help to reduce individual and social risks of bilingualism and multilingualism and stimulate its positive impact on the individual and society.