The current study examines associations between self- and teacher-rated temperament traits (activity, inhibition, negative emotionality, persistence, distractibility, and mood) and mathematics grades. The sample includes 310 ninth grade students (mean age 15.0) from several schools in Finland. Analyses were conducted with multilevel modeling. Except for mood, all temperament traits were associated with math grades independent of motivation and standardized cognitive ability test performance (intelligence). However, some relations were found only for teacher-reports and some only for student-reports. The rater dependent differences are of interest and emphasize a need for data from multiple raters before drawing conclusions on how temperament relates to school grades. The results suggest that temperament should be taken into account in schooling and in teacher education. (Contains 5 tables.)