The authors examined whether self-concept, self-efficacy, and self-esteem show differential predictive utility for academic achievement across age groups and domains. More specifically, the relationships of 3 self-constructs with achievement were examined in mathematics for elementary school students and mathematics and language arts for middle school students in Korea. Task value and test anxiety were hypothesized to mediate these relationships. Consistent with previous reports, domain-specific self-constructs such as self-efficacy and self-concept were better predictors of task value and achievement than was general self-esteem. Task value and test anxiety significantly mediated only the relationships of self-efficacy assessed by the Bandura-type scale to achievement. These domain-specific relationships tended to be stronger for middle school than elementary school students and in mathematics than language arts. (Contains 4 figures and 5 tables.)