Cyberbullying in adolescents is considered as a highly relevant topic nowadays, and yet little is still known in terms of predictors and outcomes. In this study, an incidental sample 624 adolescents (55% girls, 45% boys, ranging between 12 and 19 years of age was evaluated on two occasions separated by a one-year period, to measure cyberbullying, as well as possible personality predictors (big five, attachment styles) and possible psychosocial outcomes (self-esteem, emotional well-being, drug use and aggressive behaviour). The results indicate that low agreeableness predicts an increase in cyberaggression while fearful/preoccupied attachment predicts an increase in cybervictimization. In addition, cyberaggression predicts a decrease in self-esteem and an increase in alcohol consumption; cybervictimization predicts an increase in alcohol and tobacco consumption. Therefore, this study suggests that predictors of cyberbullying can be identified, and that cyberbullying is associated with unfavourable outcomes over time, which should be considered by intervention programs.