OBJECTIVE: Existing research on the relationships between social network sites (SNS) usage, cyberbullying perpetration, and adolescent depression has predominantly employed cross-sectional methodologies. Limited studies have delved into the bidirectional dynamics among these variables. This study aimed to fill this gap by employing a longitudinal approach to examine the reciprocal associations between SNS usage, cyberbullying perpetration, and adolescent depression. METHOD: A sample of 424 Chinese adolescents (55.9% boys
RESULTS: Cyberbullying perpetration was found to positively predict SNS usage and depression 6 months later, while depression positively predicted cyberbullying perpetration 6 months later. CONCLUSIONS: This study demonstrated the bidirectional associations between cyberbullying perpetration and depression, and the unidirectional associations between cyberbullying perpetration and SNS usage. This study extends cross-sectional observations by confirming the unique longitudinal associations between SNS usage, cyberbullying perpetration, and adolescent depression. (PsycInfo Database Record (c) 2025 APA, all rights reserved).