Cyberbullying, or aggression through electronic means towards a victim who cannot easily defend themselves, has become increasingly common in society. Researchers have shown that personality disorders and jealousy in close relationships may increase the likelihood that individuals will use aggression against their peers. However, no known research has examined the relationship between personality disorders, jealousy, and cyberbullying behaviors. The current study addresses this gap by examining associations between borderline personality disorder features, jealousy, and cyberbullying behaviors in adolescents. The sample includes 106 adolescents (53 males) with a mean age of 16.1 years (SD = .49), who completed self-report measures of borderline personality features, jealousy, and cyberbullying. Higher levels of borderline personality disorder features were associated with increased levels of cyberbullying behaviors. Jealousy fully mediated the relationship between borderline personality disorder features and cyberbullying behaviors. Limitations, directions for future research, and implications for society, intervention, and treatment are discussed. (C) 2015 Elsevier Ltd. All rights reserved.