Abstract
In the present study, we investigated the relationship between friendship quality (dimensions) and non-suicidal self-injury (NSSI) as well as the moderating role of gender and age in this relationship. The sample consisted of 463 children and adolescents (50.10% female, age range: 9–17 years). Friendship quality and NSSI were measured using the Friendship Qualities Scale (FQS; Bukowski, Hoza, & Boivin, 1994) and the Self Harm Inventory (SHI; Sansone, Wiederman, & Sansone, 1998), respectively. Overall, total friendship quality and NSSI were significantly and negatively related. Additionally, the relationship between total friendship quality and NSSI was moderated by gender and age. Specifically, girls with low friendship quality reported more NSSI; whereas for boys an opposite effect was found. As for age, friendship quality and NSSI were positively related in older participants. In younger participants, a relationship between friendship quality and NSSI seemed rather absent. This study highlights the important association between friendship quality and NSSI, as well as gender- and age-related differences in this association, which should be taken into account in the prevention and treatment of NSSI.