In this study, predictions were tested from Marsh's (1986) internal/external (I/E) frame of reference model (measuring cognitive dimensions of math and verbal self-concepts), and gender differences in the structure of academic self-concept were examined through path analyses of data from 231 Norwegian sixth-grade students (117 boys and 114 girls). Math and verbal self-concepts on a cognitive level were defined as success expectations on defined tasks. No strong support was found for the I/E model: Math and verbal self-concepts were highly correlated, and no significant negative direct effects were found of verbal achievement on math self-concept or of math achievement on verbal self-concept for boys, although a negative direct effect of verbal achievement on math self-concept was found for girls. The results differed from previous research measuring evaluative dimensions of math and verbal self-concepts, suggesting either remarkable cultural differences or that academic self-concepts are more complex than has been assumed. The structure of self-concept differed for boys and girls; math and verbal self-concepts related differently to general academic self-concept. The gender differences are discussed in terms of sex stereotypes. This study has implications for research on academic self-concept and gender differences.