This study analyzed the mediating role that implicit theories of intelligence and academic self-efficacy may play in the relationship between psychopathology and mathematical performance. The sample consisted of 838 students from first and second year of high school. A numerical calculation test was applied, followed by psychopathology self-report scales, implicit theories of intelligence, and academic self-efficacy. Serial multiple mediation models were tested. The results showed a complete mediation of the effect of psychopathology on mathematical performance through implicit theories of intelligence and academic self-efficacy. The effect of entity theories of intelligence on mathematical performance was both direct and through academic self-efficacy, whereas the effect of incremental theories of intelligence was only through academic self-efficacy. Identifying the variables that mediate the relationship in question is crucial to develop targeted interventions to prevent the development of a vicious circle between psychopathology and poor school performance.