The dual-factor model of mental health (i.e., the presence of psychological well-being along with the absence of distress) and its association with academic performance over time has been barely studied in the adolescent population, as most of the prior research focuses on psychological well-being or distress indicators in isolation. The current study analyzed the bidirectional longitudinal association between the dual-factor model of mental health and academic performance in adolescents, comprising a longitudinal assessment 2 years apart. A total of 266 secondary school students (13.9 ± 0.3 years at baseline) from Deporte, ADOlescencia y Salud study were assessed. Mental health was assessed through the Behavior Assessment System for Children and Adolescents. Academic performance was assessed throughacademic grades and the Test of Educational Abilities. A cross-lagged modeling approach was used to examine the bidirectional longitudinal association between mental health and academic performance. Higher academic performance at baseline was associated with better mental health over time, but not vice versa, since this association was not bidirectional. Results suggest that academic performance is an important target for developing educational interventions, as it shapes adolescents' mental health at 2 years of follow-up. The overall picture of students' mental health and academic performance was analyzed. Academic performance may be a predictor of adolescents' mental health status. Mental health may not be a predictor of adolescents' academic performance. Good mental health should be promoted among youth with low academic performance.