Background and aims: Problematic Internet Use (PIU) might be a potential mental health problem. Few studies have investigated the relative contribution of individual and family factors in the development of PIU in early adolescence. The aim of the current study was to model the relationship between attachment styles, negative beliefs about worry, and PIU in early adolescence. Methods: Five hundred and thirty-eight Italian early adolescents (51% females, M age 5 12.7 years, SD 5 0.87) were included in this study. The pattern of relationships specified by the theoretical model was examined through path analysis. Results: Results showed that avoidance (mother) and anxiety (father) were directly associated with PIU. Anxiety (mother) and avoidance (father) were indirectly associated with PIU via negative beliefs about worry. Discussion and conclusions: Overall, our findings show that attachment toward mother and father are differently linked to PIU and that negative beliefs about worry may play a mediating role in the association between attachment and PIU. Findings are discussed within clinical and preventive implications.  Kulcsszavak: problematic internet use, early adolescence, attachment, metacognitions