The adolescent antisocial phenomenon is an important matter for our society due to the increase in frequency and severity of deviant conducts during a developmental stage when individuals face multiple changes. Although most research focuses on male offending, gender differences in antisocial behaviour have been widely recognised. It is important to deepen our knowledge of antisocial behaviour in adolescent males and females, through its related factors and understand gender specificities. We present a research on antisocial manifestations and their relation with gender, age, socioeconomic status, personality, social skills, self-concept, and family environment in a sample of 489 students between 9 and 17 years old (60.5% females). Results show common factors that explain why boys and girls have higher antisocial tendencies: psychoticism and social conformity. In girls self-control was also a factor contributing to determine female antisocial tendency. Significant correlations between antisocial behaviour, age, personality, social skills, self-concept and family environment in boys and girls reveal the importance of individual dispositions. We conclude that there is unexpected equality in contemporary male and female adolescent experiences. Nevertheless, differences in other variables correlated with antisocial behaviour indicate different personal resources and coping mechanisms in boys and that should be addressed in future interventions and longitudinal studies.