The monograph is devoted to the description of research on social network addiction conducted by the author (alone and with co-authors) during the years 2020-2022. The development of a reliable and valid questionnaire of social network addiction is presented. A three-factor model of addiction to social networks was constructed in order to study the structure of addiction to social networks. With the help of the developed questionnaire of social network addiction and its factor model the properties and relations of social network addiction with personal characteristics and mental states and properties of its victims, with signs of psychological well-being of men and women, boys and girls, college students and university students in Russian, Belarusian and Ukrainian societies were studied. The analytical review of foreign studies of addiction to social networks. The number of research participants is more than 4000. The number of sources used - more than 300. The abstracts of the studies in Russian and English are presented.