The Russian Academy of Sciences Library (RASL) is a unique institution being at the same time one of the largest libraries to provide research information support in various fields, and a scientific institution of the Russian Academy of Sciences carrying on its own research projects in a number of scientific areas. An important direction of the RASL's activity is science popularization. To satisfy users by information services and to communicate with professionals, social networks are increasingly used. A task of RASL's activities in social networks is informing about the library's possibilities and attracting young readers. Joint analysis of the functionality and user audience of common social networks and library's objectives has justified choosing VKontakte, Facebook, Instagram for RASL's representation in social media. The authors reveal peculiarities of the target audience for each networks, develop the publication plan taking into account the specificity of the target audience and the type of published information. The main RASL's representation in social networks at the initial stage of activity has been chosen VKontakte as the most effective platform in the Russian Internet segment. The paper shows statistical indicators of VKontakte RASL's page got by using the built-in functions of the service (www.vk.com), which permit to analyze the activity for 9 months since the beginning of its work. The obtained demographic and quantitative indicators confirm the activity effectiveness that consists in increasing the visitors’ number at the page. The audience age analysis shows that above 2/3 of readers are young people under 35 years old. This circumstance corresponds to the desired target audience. The official library site analysis based on Google Analytics indicates an increase in the number of visitors to the library website (www.rasl.ru) from social networks.