The aim of this study was to explore the effects of a two-year intervention grounded in the ability model of emotional intelligence (EI) on aggression and empathy among adolescents. Eight Spanish public schools volunteered to participate in the research. A total of 590 adolescents (46% boys) were randomly assigned to either the EI training group or control group conditions. Students in the EI training group reported lower levels of physical/verbal aggression, anger, hostility, personal distress and fantasy compared to students in the control group. Additionally, the EI program was particularly effective for males' empathic abilities. These findings confirm the effectiveness of social and emotional learning interventions in Spanish academic contexts and extend the literature of gender-related differences during adolescence. Study limitations and future research directions are also considered.