OBJECTIVE: Previous research suggests that cognitive functioning is associated with the risk of several adult psychiatric disorders. In this study we investigated whether adolescents who perform worse than expected at secondary school are at a higher risk for general mental health problems. METHODS: In a cross-sectional survey comprising 10,866 Dutch adolescents aged 13 to 16 years, underachievement at secondary school was defined as the discrepancy between predicted school grade and actual grade 1 or 3 years later. Mental health problems were assessed using the Strengths and Difficulties Questionnaire. We investigated the association of underachievement with mental health problems using logistic regression, adjusting for potential confounders. RESULTS: Underachievement was associated with general psychopathology in pupils aged 13 to 14 years (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.47-2.37) and in pupils aged 15 to 16 years (OR, 2.05; 95% CI, 1.67-2.52) in a multivariate analysis including sociodemographic factors. The association between underachievement and mental health problems was attenuated when school factors such as teacher advice and interaction between underachievement and teacher advice were added, but underachievement remained significantly associated with mental health problems in adolescents in the higher educational tracks (pupils aged 13-14 years: OR, 2.22; 95% CI, 1.07-4.60 and OR, 2.41; 95% CI, 1.10-5.30, age 15-16 years: OR, 2.63; 95% CI, 1.38-5.03). In the multivariate analysis including the interaction between underachievement and teacher advice, a significant interaction effect occurs between underachievement and teacher advice in the higher tracks. Values of OR and CI are given for each significant interaction term. In the younger age group (pupils aged 13-14 years) this results in 2 sets of OR and CI. This association was most pronounced for the hyperactivity subscale of the Strengths and Difficulties Questionnaire. CONCLUSIONS: Underachievement at secondary school is associated with general mental health problems, especially with hyperactivity symptoms, in pupils who started at high educational tracks.