This study examines the developmental trajectories of ability and trait emotional intelligence (EI) in the Portuguese secondary school. Within a three-wave longitudinal design, 395 students (M[subscript age] = 15.4; SD = 0.74) completed both the Emotional Skills and Competence Questionnaire (ESCQ) and the Vocabulary of Emotions Test (VET). Results revealed that EI exhibited different developmental trajectories during late adolescence according to the type of measure used, while students' VET levels evidenced an increase during secondary school, their ESCQ levels remained stable during this period. Moreover, students' gender, verbal indicator, and type of school (public vs. private) have no significant effect on their rate of EI change, whereas students from lower sociocultural and lower professional status backgrounds demonstrated significantly greater increases on the ESCQ and VET compared to higher status adolescents. The results are examined in the context of adolescent emotional development.