Non-suicidal self-injury (NSSI) is common among adolescents and is associated with a range of detrimental consequences. Family, teachers, and friends are essential sources of social support for adolescents. Increased social support from these sources may reduce NSSI behaviors among adolescents. However, it is uncertain if each source of social support retains its significance when their influences are evaluated simultaneously, and how each source influences the others to impact NSSI behaviors. To address this gap, this research investigated the direct and indirect effects of each source of social support on adolescent NSSI using cross-lagged panel model (CLPM), as well as whether these relationships varied by sex. A total of 3098 Chinese adolescents with a range of 10 to 15 years old (Mage = 13.27, SD = 0.73, 42.4% girls) completed assessments on three waves across approximately two years. The results indicated that teacher support compared to family and friend support showed the strongest association with NSSI behaviors and mediated the relationship between family support and NSSI. These findings highlight teacher support as a hub in the role of social support on NSSI and emphasize the importance of the connections between teacher and family support.
