The purpose of the present Bachelor thesis “Bullying behaviors among adolescents on Facebook: a case study of girls from Otepää Gymnasium“, was to explore to what extent do adolescents use Facebook to exhibit bullying behavior towards other teens, which methods do they use and how are things that happen on Facebook related to the offline world. The main concept used in this thesis is bullying behavior, which expresses posts generated by adolescents consisting of bullying, conflicts, drama and gossip. Throughout the thesis the main authors I’ve used were danah boyd and Alice Marwick and their qualitative studies, background information was provided by EU Kids Online II surveys. In the first chapter a review of theories and earlier qualitative studies of this subject was presented. The relationships between adolescents in the offline world, their practices of internet use and continuously increasing cyber-bullying, in relation to the development of the information society, were studied more closely. An overview of teens’ usage of social network sites and their bullying behavior was also given. The studying of adolescents’ bullying behavior on Facebook was based on focus-group interviews which were carried out with semi-structured questionnaires and conducted among 10-12 grade female students from Otepää Gymnasium. Data was analyzed by using the cross-case method, which allows to study answers across respondents. Received data was coded and presented in the findings with illustrative quotes. The findings of the study suggest that adolescents use Facebook quite often to show their bullying behavior. Teenagers themselves do not want to use the word bullying to describe their actions, because bullying is associated with physical action and is considered an activity common amongst younger children. They prefer to use the word drama since according to adolescents, drama is more innocent than bullying. Teens also describe their activities on Facebook as having fun amongst peers or humor. That kind of behavior is supported by the fact that people who make fun of each other are acquaintances or friends, so adolescents assume that the other person knows that they are just joking around. Adolescents pick on each other mostly by writing comments under posted images, pictures etc. It appeared that bullying behavior also occurs when a person wants to show off his/her success. For example, when somebody uploads a picture where he demonstrates pumped up muscles, the auditorium begins to gloat about it or writes sarcastic comments. From the findings we can conclude that certain people always deserve ironical comments, and that the auditorium is waiting for pictures or status updates to lash out. Bullies are characterized by a desire to stand out, a need for attention and an understanding that they are somehow better than others. Arrogance often leads to great conflicts. Although teenagers have both parents and teachers on their contact lists, an adult intervention in case of bullying is not common on Facebook. However, in some cases teachers in school have talked to students about improper party pictures. Because teens don’t see any major problems in their activity, some girls who participated in the present study think that teachers should mind their own business. Some girls see that instructions are necessary but should be aimed at middle school students. Spiteful postings on Facebook show that many of the subjects and themes are transferred from ordinary life, but on the other hand do not show that bullying behavior moves in between online and offline environments, which means that the conflicts that are cleared up on Facebook, will remain there, and those that are dissected in everyday life, are solved there. The difference comes in the point that generally bullying behavior expressed on Facebook does not find a solution, while in the offline environment sooner or later adolescents seek reconciliation. This, however, happens if a conflict has arisen in between friends. Adolescents see that internet adds power to bullying behavior, since sitting behind a computer at home teens do not have to worry about someone hurting them because of inappropriate or despiteful comments. Therefore comments are more bold and colorful than in everyday life. Since it is an important, but little studied subject in the context of Estonia, the area needs to be developed, particularly in the form of expansion of the sample, which allows us to understand how boys and middle school students see and explain bullying behavior on Facebook., http://www.ester.ee/record=b4069395~S1*est