The work group formed on behalf of Ministry of Family, Veterans' Affairs and Intergenerational Solidarity of the Republic of Croatia has provided a unique definition of the problem of behavioral disorders. The specified disorders in children and young people are typified under 'a basic term that covers a continuum of behavior typesranging from behaviorscharacterised as more simple, less harmful to self and others, to those defined and/or sanctioned by regulations and characterised as more severe due to their cosequences and needof treatment'. (Koller-Trbović, N., Žižak, A., Jeđud-Borić, I. (2011) This thesis contains two main sections. 1. The theoretical framework of the thesis deals with characteristics related to the topic: definitions, classifications, factors of behavioral disorders, description of the most common externalising and internalizing behavioral disorders and strategies to prevent the disorders. 2. The research section. The aim of the research was to determine differences in prevalence of behavioral disorders in second and fourth graders in elementary school regarding their gender. The research has been conducted in four Zadar elementary schools, and the total sample consists of 158 pupils. The first hypothesis claims that active types of behavioral disorders are more common in males than in females. This hypothesis has been confirmed. The second hypothesis claims that teachers are not satisfied with the cooperation with parents of children with behavioral disorders, as well as the cooperation with children counsellors at schools. This hypothesis has been refuted by research results. The third hypothesis claims that students with behavioral disorders are not involved extra-curricular activities . This hypothesis has also been confirmed.