In relation to a sample of 1,092 Italian adolescents (50.9% females), the present study aims to: (a) analyze the most parsimonious structure of the cyberbullying and cybervictimization construct in male and female Italian adolescents through confirmatory factor analysis; and (b) analyze the severity and the discrimination parameters of each act using the item response theory. Results showed that the structure of the cyberbullying scale for perpetrated and received behaviors in both genders could best be represented by a monodimensional model where each item lies on a continuum of severity of aggressive acts. For both genders, the less severe acts are silent/prank calls and insults on instant messaging, and the most severe acts are unpleasant pictures/photos on Web sites, phone pictures/photos/videos of intimate scenes, and phone pictures/photos/videos of violent scenes. The items nasty text messages, nasty or rude e-mails, insults on Web sites, insults in chatrooms, and insults on blogs range from moderate to high levels of severity. Regarding the discrimination level of the acts, several items emerged as good indicators at various levels of cyberbullying and cybervictimization severity, with the exception of silent/prank calls. Furthermore, gender specificities underlined that the visual items can be considered good indicators of severe cyberbullies and cybervictims only in males. This information can help in understanding better the nature of the phenomenon, its severity in a given population, and to plan more specific prevention and intervention strategies.