This study examined the generalizability of the internal/external (I/E) frame of reference model of academic self-concept development. The "external" component of the model refers to comparing one's achievement with one's peers; in LISREL causal modeling, this external comparison is presented as positive paths. The "internal" component refers to comparing one's achievement in one academic area to another area to determine one's ability; in LISREL causal modeling, this internal comparison is presented as negative paths. The two paths should cause a student's math and verbal self-concepts to be uncorrelated, even though achievement in these areas is highly correlated. The I/E model has been demonstrated on Australian and Canadian children and adolescents. This study sought to determine whether the model was generalizable to an American sample and across different measures of academic self-confidence, and whether there were gender differences in the operation of the I/E model. For 152 seventh and eight graders in a Florida middle school, math and language arts grades were obtained to measure achievement, and self-description questionnaires were administered to measure self-confidence. Verbal and math self-concepts were uncorrelated, and the positive paths from math and verbal achievement to math and verbal self-concept were both significant. However, the negative path from math achievement to verbal self-confidence was not significant. No evidence of gender difference was found. (TM)