The period of adolescence is a period of a person's development and transition to adulthood. One of the most important tasks of that period is development of a healthy self-image. Social networks are a ubiquitous part of today and a way for many adolescents to spend their free time. The main goal of the research was to examine the characteristics of adolescents' self-esteem. The paper problematizes the relationship between self-esteem and social networks and the relationship between self-esteem and socio-demographic characteristics with an emphasis on risky behavior. The research was conducted in December 2021 in Zagreb with a survey questionnaire prepared for the purposes of the paper. It was conducted on a sample of 368 respondents (49.7% male, 48.1% female and 2.2% of others who did not indicate gender). The respondents were students aged 12 to 17, ie students of the seventh (25%) and eighth grade (21.5%) of three primary schools and students of the first (26.1%) and second grade (27.4%) of one high school in the city of Zagreb. Research has found that adolescents have a positive self-image. It was also found that, given the socio-demographic characteristics (gender, class), they have different habits and behaviors on social networks, as well as that adolescents who use social networks more report lower self-esteem. The results of the research pointed out the importance and future of media education and the importance of organizing the free time of young people. Media education is a tool that would raise awareness of the impact of social networks on the individual, and the organization of leisure time would contribute to the development of a positive slef-image.