Background: Parents consult with schools on how to help their children succeed, but schools rarely consult with parents, even though most parents have considerable expertise concerning their children's thoughts, feelings, and abilities. Aims: This study compares the prediction of academic achievement from self- and parent-ratings of feelings towards school (both positive and negative), life satisfaction, and the conscientiousness facet of industriousness for 357 adolescents. Sample: The student sample consisted of 383 participants (194 boys) mostly aged between 12 and 14. The parent sample consisted of 374 participants, 83% of whom were mothers. Method: Self-report and other-report scales measuring the above-mentioned constructs were administered to students and parents. Hierarchical regression analysis was used to test hypotheses concerning the incremental validity of parent-ratings. Results: Self-ratings explained 28.6% of the variance in grade point average (GPA) with parent-ratings explaining an additional 12.1%. The incremental effect was strongest for industriousness. Conclusion: These results suggest that parent-reports are often more accurate than adolescent self-reports, but that both methods of assessment make unique contributions to the explanation of variance in school grades. Parental understanding constitutes a relatively untapped reservoir of knowledge available to teachers, school counsellors and administrators, education policy makers, and beyond. It makes sense to ask parents about their children when assessing those individual differences that contribute to better educational outcomes.