The article presents the results of research into the relationship between the propensity to various forms of cyber-aggression and the social intelligence (social awareness and social skills) of adolescents. Cyber-aggression is understood as form of destructive behavior on the Internet. The types of cyber-aggression are distinguished based on the typological model proposed by K.C. Runions who describes cyber-aggression of adolescents through their motivational goals and behavioral self-control capacities. Data collection was carried out using the “Typology of Cyber-Aggression” questionnaire and “The Tromsø social intelligence scale”. Both questionnaires were adapted for the Russian-speaking sample of adolescents. The study involved 317 students of 5th–9th grades of secondary schools in St Petersburg aged 11–16 years. Participation in the study was voluntary. Informed parental consent was obtained in respect of each student. The study showed that students are prone to cyber-aggression during the entire adolescence period—especially to the controlled-aversive form of cyber-aggression. In general, adolescents were more likely to show aggression as “revenge” on their internet communication partner. The study made it possible to record the relationship between the propensity to cyber-aggression, social awareness, social skills and social intelligences as a whole. Correlation between the propensity to cyber-aggression and social skills was noted only for 12–13 year olds. For 15 year olds, there was not a single association between cyber-aggression and the predictors in question. We used regression analysis to obtain a statistically significant regression model both for cyber-aggression in general and for each of its form in particular, but the obtained predictors do not have a strong influence on the propensity to manifest cyber-aggression. Based on this study, we hypothesized that cyber-aggression might have various psychological causes. Thus, there is a need for a differentiated approach to the prevention and correction of adolescent cyber-aggression.