The aim of this paper was to examine to what extent and for what purposes the students of the three high schools in Sinj use the media and media devices and to what extent they have developed media literacy competencies. The theoretical part of the paper discusses the role that the mass media has in modern society and the importance of media literacy as a new form of literacy of the 21st century. Furthermore, it is shown how much and in which teaching areas media literacy is represented in the educational system. The relationship between adolescents and the media is also problematized. The sample of this research consisted of 164 students from three high schools in Sinj. The research was conducted using the online survey questionnaire and the data processing included descriptive statistics. Some of the most important results of this research are that all students use the Internet and mobile devices daily. About two-thirds of the students spend more than four hours a day using media and almost all of them use it primarily for entertainment purposes. Students are aware of the manipulative character of the media, the stereotypical portrayal of certain groups in the media, and the objectification and sexualization of the human body. Students critically reflect on and interpret media messages and content. A quarter of the surveyed students state that they have not learned about media literacy competencies during their schooling so far. Most of those who learned about media literacy, learned about it through the teaching of the Croatian language, computer science and through a foreign language.