This study examines the relationship between empathy, pro-social behaviour, mentalization bias, and behavioural disorders (BD) in 7 to 12-year-old boys. Fifty-one boys, presenting different levels of BD, and their parents, participated in the research. Children completed self-administered measures on empathy and mentalization bias. The parents completed questionnaires on empathy, pro-social behaviour, and BD regarding their children. The results show that negative mentalization bias and pro-social behaviour predict 24.5 % of the BD’s variance. Empathy would be considered a mediating variable between pro-social behaviour and BD. The results would be used to improve prevention programs and interventions offered to school-age children with BD.