The big-fish-little-pond model (BFLP) and the internal/external (I/E) frame of reference model highlight the great influence of social and dimensional comparison effects on academic self-concepts (ASCs). In the present study of 291 elementary school children in Grade 2, both models were tested in a unifying framework based on math and reading self-concepts and achievements. The aim was to test the BFLP model, the I/E model, and the revisited I/E model integrating both the predictions of the BFLP model and the I/E model. Results showed significantly positive within-domain achievement-self-concept relations, but no significantly negative cross-domain achievement-self-concept relations. Moreover, there were higher relations between individual achievements than between ASCs, while no support was found for positive compensatory effects of class-average achievements on ASCs. The within and cross-domain effects were generally smaller than the ones reported for older students. This research indicates that social and dimensional comparison effects on ASCs are of less importance in second graders.