The aim of this thesis is to explore the connection between the prevention of behavioural problems and the excessive use of social networks. The thesis introduction contains a general overview of the prevention including descriptions of its various levels. The part explaining the prevention in general is followed by the section clarifying the concept of a social network supported by the list of most frequently used social networks globally. The underlying standpoint of the thesis is that a specific part of the population in Republic of Croatia suffers from the excessive use of social networks. Relevant data in support of this standpoint were collected through the on-line questionnaire via LimeSurvey service. These data included usage habits, attitudes and positive / negative consequences of using social networks of the general population. On-line questionnaire was based on the previous questionnaire and quantitative research “How addicted to Facebook are you?” (Badurina and Prpic, 2015) by way of broadening the questionnaire and focusing on all social networks. The application of such a method represents an efficient way to remedy the key deficiency in the previous research -exclusive focus on a single social network - Facebook. The results of this research clearly present usage habits, attitudes and positive / negative consequences of using social networks by the general population in the Republic of Croatia. The thesis also contains recommendations for a part of the population qualified as excessive users of social networks or population affected by specific negative consequences stemming from the use of social networks visible in the behaviour. These recommendations should contribute to the social networks use reduction and greater individual responsibility when the social networks are used. The aforementioned recommendations were produced on the basis of existing data relative to the prevention of behavioural problems which will be connected in this thesis with the results obtained in the survey conducted for this purpose.