Introduction: In this cross-sectional, descriptive research we studied the relation between three psychological variables (anxiety, depression and attention) in order to analyze their possible association with and predictive power for academic achievement (as expressed in school grades) in a sample of secondary students. Method: For this purpose we worked with a sample of 98 randomly selected students, ages 12-16 years, enrolled at two secondary schools in the city of Granada. Results: The results indicate a significant association between depression and anxiety in parts of the sample, as well as a significant inverse association between depression and academic performance. The analysis of gender differences showed significant differences between men and women in the overall grade point average (higher in women than in men) as well as in depression, with more depressive symptoms in boys. There were no significant differences in anxiety or attention deficit between men and women. Regression analysis indicated that moderate levels of anxiety are associated with better academic performance, with no association observed between anxiety and selective attention. Discussion and Conclusion: It is important to monitor levels of depressive symptomatology and emotional disturbance in secondary students, since early detection makes it possible to provide suitable care and to reduce these variables' role in academic failure, or at the least, to improve students' academic performance. (Contains 6 tables and 1 footnote.)