Background: Given the pressure that educators and policy makers are under to achieve academic standards for students, understanding the relationship of academic success to various aspects of health is important. The international Health Behavior in School-Aged Children (HBSC) questionnaire, being used in 41 countries with different school and grading systems, has contained an item assessing perceived school performance (PSP) since 1986. Whereas the test-retest reliability of this item has been reported previously, we determined its convergent and discriminant validity. Methods: This cross-sectional study used anonymous self-report data from Austrian (N = 266), Norwegian (N = 240), and Canadian (N = 9,717) samples. Students were between 10 and 17 years old. PSP responses were compared to the self-reported average school grades in 6 subjects (Austria) or 8 subjects (Norway), respectively, or to a general, 5-category-based appraisal of most recent school grades (Canada). Results: Correlations between PSP and self-reported average school grade scores were between 0.51 and 0.65, representing large effect sizes. Differences between the median school grades in the 4 categories of the PSP item were statistically significant in all 3 samples. The PSP item showed predominantly small associations with some randomly selected HBSC items or scales designed to measure different concepts. Conclusions: The PSP item seems to be a valid and useful question that can distinguish groups of respondents that get good grades at school from those that do not. The meaning of PSP may be context-specific and may have different connotations across student populations from different countries with different school systems. (Contains 4 tables.)