Lately, online social networks became very popular, and are part of people's everyday lives. They are especially appealing to adolescents. Since adolescence is a period of discovering one's own identity, these two phenomena became the subject of interest for many researchers. This paper was aimed at investigating the correlation between different dimensions of self-perception and adolescents' habits and behavior when using online social networks. The results show that adolescents' self-perception is mostly positive. From the data about their habits and behavior on Facebook, it can be seen that adolescents usually have one user profile through which they share different contents with a large number of online friends, often uncovering private information, leading themselves to potentially dangerous situations. Adolescents that participated in this study rarely had negative experiences while using this particular social network. Only communication with unknown persons became highlighted as being experienced by a greater number of participants. Obtained data showed there is statistically significant correlation between self-perception and habits and behavior on Facebook, although the correlations are weak. Ultimately, results point to the need for educating both children and parents regarding safe internet use, the need to encourage positive self-image development, organizing quality spare time for children and youth, and strengthening the culture of socializing in the real world.