Social networks are an inevitable part of everyday life, especially for adolescents who are considered to be their main user group. Adolescence is a period of discovering one's own identity and social networks can have a large influence in that process. Adolescents daily spend more and more time using social networks, so they become their main source of information and the method of communication. The aim of this paper is to present the role that social networks activities can have in the formation of self-image, and also to describe the role of social work in working with young people in the context of virtual environment. The first part of the paper is about social networks, their historic development, basic characteristics and their advantages and disadvantages. The next part of the paper defines self-image, describes how it is formed and which social phenomena have the largest impact on that formation. Social networks can have a large impact on self-image of adolescents because of the process of social comparison and because adolescents want to be approved by their friends and peers. The final section of the paper is about the role of social work as a profession, it describes how social workers can help young people with problems that arise as a result of using social networks and why online environment is suitable for working with adolescents.