The theoretical part of the paper includes definitions of behavioural disorders, the role of parents and family as the child's closest community in their development, and the influence of peers that becomes equal to, and sometimes even exceeds, the influence of parents. Furthermore, risk and protective factors within the family and school environment are also listed and described. The following chapter is devoted to types of student behaviour, ranging from prosocial to problematic. It is followed by a description of the levels and aspects of prevention, with a focus on universal prevention programmes aimed at narcotics, violence and risky sexual behaviour. The research part of the paper presents the results of a study conducted among eighth grade students from Antun Gustav Matoš primary school and students of the Ivan Domac School of Economics and Commerce in Vinkovci. The goals of the research are to determine the link between behavioural disorders and the social life of respondents, i.e. to gain insight into the influence a problematic peer group has on an individual's behaviour, the level of acceptance an individual with behavioural disorders enjoys in their peer group, as well as the individual’s influence on the group. Finally, it aims to determine the parental influence on the child's behaviour within the peer group. Hypotheses were set for each of these components, and were rejected after performing the Z-test and the upper acceptance limit test. In addition to statistical data processing, a descriptive analysis of each answer is presented, meaning that the answers of the two groups are compared. The analysis is followed by a discussion that includes a comparison of the obtained research results with similar studies, primarily the ESPAD research.